חומר רקע
© Oxera 2022
A study of the effectiveness of travel restrictions in the EEA
Oxera and Edge Health
1
A study of the effectiveness of
travel restrictions in the EEA
—
Prepared for ACI EUROPE and IATA
Oxera and Edge Health
24 February 2022
Executive summary
—
There have been extensive travel restrictions in place across Europe over
the last two years, ranging from mandatory quarantines to pre-departure
testing and on-arrival testing. Despite these travel restrictions, Europe
has experienced significant waves of COVID-19.
While the current wave of infections associated with the Omicron variant
is subsiding in most European countries, new Variants of Concern (VOCs)
are likely to continue to emerge. However, nearly two years on from the
start of the pandemic, there is a question about whether implementing
travel restrictions to protect domestic populations against COVID-19 is a
useful and proportionate approach.
Indeed, analysis shows that travel restrictions have failed to prevent the
spread of COVID-19.¹ The International Health Regulation Emergency
Committee of the World Health Organisation (WHO) also recently
highlighted the failure of travel restrictions to limit the importation of
VOCs.²
As we look to a world where COVID-19 is endemic, it is relevant to
consider the role of air passenger travel restrictions in limiting the
importation of COVID-19, particularly as a result of new VOCs.
The effectiveness of travel restrictions is further reduced
when a variant is more infectious.
If the introduction of travel restrictions is delayed by even one
week, the benefit of travel restrictions in terms of delaying the
peak of COVID-19 cases declines by half, to a maximum of
two days from the day the variant is first imported.
1 For example, see Oxera and Edge Health (2022), ‘Impact of travel restrictions on Omicron in Italy and Finland’, Prepared for ACI Europe and IATA, 26 January; Oxera and Edge
Health (2022), ‘A framework for considering the impact of air travel restrictions on the UK’, Prepared for Manchester Airports Group and Airlines UK, January.
2 In a recent meeting, the WHO noted that: ‘The failure of travel restrictions introduced after the detection and reporting of Omicron variant to limit international spread of
Omicron demonstrates the ineffectiveness of such measures over time. Travel measures (e.g. masking, testing, isolation/quarantine, and vaccination) should be based on risk
assessments and avoid placing the financial burden on international travellers’. World Health Organisation (2022), ‘Statement on the tenth meeting of the International Health
Regulations (2005) Emergency Committee regarding the coronavirus disease (COVID-19) pandemic’, 19 January, https://www.who.int/news/item/19-01-2022-statement-on-the-
tenth-meeting-of-the-international-health-regulations-(2005)-emergency-committee-regarding-the-coronavirus-disease-(covid-19)-pandemic.
There is unlikely to be a demonstrable benefit associated with introducing
travel restrictions in response to new variants.
This is consistent with experience since the beginning of the pandemic that
indicates that it is difficult to identify a variant as a VOC sufficiently quickly to be
able to introduce travel restrictions that have an impact.
4d
Even if travel restrictions were pre-emptively introduced, or could
be put in place on the day the variant is first imported, they would
not have an impact on limiting the peak of cases, and would
only delay the peak by a maximum of four days. If we consider
this timing in the context of Omicron, most European countries
did not introduce travel restrictions until a number of weeks after
Omicron was identified as a VOC by the WHO on 24 November.
© Oxera 2022
A study of the effectiveness of travel restrictions in the EEA
Oxera and Edge Health
3
Overview
1. Introduction and general principles
4
2. Analysis: scenarios and results
7
3. Conclusion
12
4. Appendix
13
Oxera Consulting LLP is a limited liability partnership registered in England no.
OC392464, registered office: Park Central, 40/41 Park End Street, Oxford OX1 1JD, UK;
in Belgium, no. 0651 990 151, branch office: Avenue Louise 81, 1050 Brussels, Belgium;
and in Italy, REA no. RM - 1530473, branch office: Via delle Quattro Fontane 15, 00184
Rome, Italy. Oxera Consulting (France) LLP, a French branch, registered office: 60
Avenue Charles de Gaulle, CS 60016, 92573 Neuilly-sur-Seine, France and registered
in Nanterre, RCS no. 844 900 407 00025. Oxera Consulting (Netherlands) LLP, a Dutch
branch, registered office: Strawinskylaan 3051, 1077 ZX Amsterdam, The Netherlands
and registered in Amsterdam, KvK no. 72446218. Oxera Consulting GmbH is registered
in Germany, no. HRB 148781 B (Local Court of Charlottenburg), registered office: Rahel-
Hirsch-Straße 10, Berlin 10557, Germany.
Although every effort has been made to ensure the accuracy of the material and the
integrity of the analysis presented herein, Oxera accepts no liability for any actions taken
on the basis of its contents.
No Oxera entity is either authorised or regulated by any Financial Authority or Regulation
within any of the countries within which it operates or provides services. Anyone
considering a specific investment should consult their own broker or other investment
adviser. Oxera accepts no liability for any specific investment decision, which must be at
the investor’s own risk.
© Oxera 2022. All rights reserved. Except for the quotation of short passages for the
purposes of criticism or review, no part may be used or reproduced without permission.
© Oxera 2022
A study of the effectiveness of travel restrictions in the EEA
Oxera and Edge Health
4
Introduction and general principles
© Oxera 2022
A study of the effectiveness of travel restrictions in the EEA
Oxera and Edge Health
5
Introduction
—
There has been a range of international travel restrictions in place across
Europe since the start of the pandemic. Countries in the European
Economic Area (EEA) have implemented different restrictions from one
another in response to the same set of circumstances. These restrictions
have also changed over time within a given country—e.g. from mandatory
quarantine, to pre-departure PCR tests, to antigen tests upon arrival.
Successful vaccination campaigns, natural immunity, and improved
treatments such as antivirals mean that many European countries have
removed or are significantly reducing local restrictions even as Omicron is
still spreading. At the same time, as of 26 January, 12 EU member states
still required vaccinated passengers to take pre-departure tests (in some
cases in addition to on-arrival tests) for intra-European travel.
More recently, some countries have started to remove travel restrictions,
and as of February 2022, only one country has travel restrictions in place.
The European Council has also adopted revised recommendations for a
common approach to travel measures for intra-EU travel as of
1 February based on an individual risk-based approach rather than the
epidemiological situation of a country or region.¹ It states that there should
be no testing or quarantine/self-isolation for fully vaccinated or recovered
travellers holding a valid EU Digital COVID Certificate (DCC).² On
22 February, the Council also adopted a proposal to facilitate extra-EU
travel.³
However, the experience with Omicron shows that countries are quick to
introduce travel restrictions once a variant is identified as a VOC,⁴ and
are then slow to remove them. Indeed, there is an Emergency Break
procedure in the Council’s recommendation allowing states to reimpose
travel restrictions in case new Variants of Concern or Interest are detected.
This is despite evidence showing that travel restrictions have not been
effective at slowing the spread of Omicron, and the significant costs of
such restrictions for passengers, the aviation sector, and the economy.
1 See European Council (2022), ‘Infographic - A common approach to COVID-19 travel measures in the EU’, https://www.consilium.europa.eu/en/infographics/covid19-travel-
measures-eu-january-2022/.
2 Unvaccinated passengers should be subject to a NAAT or rapid antigen test before arrival or within 24 hours of arriving.
³ See European Union (2021), ‘Proposal for a COUNCIL RECOMMENDATION amending Council Recommendation (EU) 2020/912 on the temporary restriction on non-essential
travel into the EU and the possible lifting of such restriction’, 26 January, https://op.europa.eu/en/publication-detail/-/publication/4dc62746-4df9-11ec-91ac-01aa75ed71a1/
language-en, and European Council (2022), ‘Infographic - COVID-19: travel from third countries into the EU ‘, 22 February, https://www.consilium.europa.eu/en/infographics/
covid19-travel-restrictions-third-countries-february2022/. For example, member states should not only accept COVID-19 vaccines that have been granted a marketing
authorisation pursuant to Regulation (EC) No 726/2004 of the European Parliament and of the Council, but also those having completed the emergency listing procedure of the
World Health Organization (WHO).
⁴ There is generally a delay between variants first being sequenced and then identified as a VOC. This means that even if travel restrictions are put in place soon after a variant is
identified as a concern, cases are already likely to have been seeded at that stage.
© Oxera 2022
A study of the effectiveness of travel restrictions in the EEA
Oxera and Edge Health
6
Looking forward, there are likely to be new VOCs. The key question
therefore concerns the role that travel restrictions can play in reducing the
spread of COVID-19, based on the data and lessons of the last two years.
It is in this context that ACI EUROPE and IATA have asked Oxera and
Edge Health to analyse the impact that travel restrictions could have going
forward. In particular, we have analysed a number of different scenarios
around the importation of VOCs and future waves of COVID-19 to help
consider:⁵
•
the extent to which travel restrictions affect the speed and peak of the
spread of COVID-19 as a result of a new variant;
•
the trigger points for bringing in, as well as removing, testing
requirements to deal with new VOCs—i.e. the critical point at which
introducing travel restrictions could have an impact and the point at
which there would be a critical mass of a VOC domestically such that
travel restrictions are no longer relevant.
This analysis helps provide information about the benefits of travel
restrictions from a public health perspective that can then be compared
with the costs that such restrictions impose on the economy.
General principles for imposing travel restrictions
—
In order to determine appropriate travel restrictions going forward, it is
important to consider the objective of such restrictions. Any restrictions
imposed should aim to minimise economic disruption. This includes all
potential issues that could arise as a result of seeding new VOCs, such
as the impact of widespread infection on health services, as well as the
disruption caused to the economy. In line with this objective, it is relevant
to consider the following key principles.
• Travel restrictions should only be imposed if they can have a
meaningful impact on the peak and/or timing of cases; otherwise they
should not be imposed at all.
• Travel restrictions should be removed once seeded cases exceed the
level beyond which such restrictions would make a material difference
to the trajectory of infections.
• The costs of imposing any restrictions should be balanced against the
benefits.
• Given the incremental cost of restrictions, they should be targeted as
much as possible.
⁵ This analysis builds on previous analysis undertaken by Oxera and Edge Health over the last year. For example, see Oxera and Edge Health (2022), ‘Impact of travel restrictions
on Omicron in Italy and Finland’, prepared for ACI EUROPE and IATA, 26 January.
© Oxera 2022
A study of the effectiveness of travel restrictions in the EEA
Oxera and Edge Health
7
Analysis: scenarios and results
© Oxera 2022
A study of the effectiveness of travel restrictions in the EEA
Oxera and Edge Health
8
Analysis
—
We have modelled a number of scenarios to consider the impact of future
air travel restrictions. The modelling includes three scenarios that reflect
the most likely outcomes over the next several months (i.e. short- and
medium-term scenarios) where variants are more infectious than Omicron
or are able to evade vaccines.
The modelling also considers a potential scenario for the longer term
(i.e. longer-term scenario). In this scenario, less infectious variants could
become dominant. However, it is difficult to predict what will happen in
the longer term (e.g. natural immunity could be greater, meaning even
less infectious variants could become dominant; or natural immunity
could wane such that Omicron becomes dominant again). Therefore, it is
important to consider the longer-term picture again as more data becomes
available.
Each scenario has been modelled for the case where traffic is back to
80% of 2019 levels, and for a sensitivity with traffic at approximately 50%
of 2019 levels. We also include a sensitivity analysis in the Appendix that
considers the impact of travel restrictions if natural immunity wanes going
forward and booster programmes are being rolled out.
We compare having pre-emptive travel restrictions, or restrictions imposed
on the day the variant is imported, to having no testing regime in place.
In particular, we consider pre-departure testing (an antigen test 48 hours
before travelling or PCR test 72 hours before travelling), which has been
the most common testing regime in European countries.
Scenarios considered
Scenario
Scenario 1
Scenario 2
Scenario 3
Scenario 4
Description of scenario
Medium term
Omicron +: variant slightly (1.25 times) more
infectious than Omicron once 20% of the population
has some natural immunity to Omicron
Vaccine escape variant: same infectiousness as
Omicron but twice the immune escape, and therefore
an Rt 1.6 times more infectious than Omicron once
20% of the population has some natural immunity to
Omicron
Omicron ++: variant significantly (2.5 times) more
infectious than Omicron once 30% of the population
has some natural immunity to Omicron
Longer term
Omicron -: variant slightly (1.25 times) more
infectious than Omicron once 25% of the population
has some natural immunity to Omicron
Rt of scenario*
3.75
4.86
7.51
3.56
Travel restrictions modelled
(i) no passenger testing or
quarantine
(ii) pre-departure antigen (48hrs)
and pre-depature PCR (72hrs)
Note: * Rt is when the variant is first seeded. We have assumed that masks and COVID-19 testing
continue in the EEA.
© Oxera 2022
A study of the effectiveness of travel restrictions in the EEA
Oxera and Edge Health
9
Results
—
Air travel restrictions do not affect the size of the peak
Introducing air passenger testing does not affect the height of the peak
of cases, relative to not having any restrictions in place. This holds even
when travel volumes are high.
Omicron +
Omicron +
No testing or quarantine
Pre-departure antigen 48hrs or PCR 72hrs
High volume
Low volume
Daily Omicron cases
Daily Omicron cases
20,000,000
15,000,000
10,000,000
5,000,000
0
20,000,000
15,000,000
10,000,000
5,000,000
0
Omicron ++
Omicron ++
Omicron -
(longer term)
Omicron -
(longer term)
Vaccine escape
variant
Vaccine escape
variant
© Oxera 2022
A study of the effectiveness of travel restrictions in the EEA
Oxera and Edge Health
10
There is a small impact of air passenger testing on the timing of the
peak; however, as the variant gets more infectious, the impact of travel
restrictions on the delay in the peak decreases
The table below shows the impact of variant infectiousness on the delay of
the peak when travel volumes are high (i.e. 80% of 2019 levels). Variants
are ordered from least to most infectious. The imposition of air passenger
testing leads to between a two- and four-day delay in the peak of cases.
This delay is measured from the day the variant is first imported, which is
likely to precede a variant being identified as a concern.
Travel restriction
Pre-departure
antigen 48hrs or
PCR 72hrs
Delay in peak relative to no
testing and quarantine (days)
4
4
2
2
Scenario
Omicron -
Omicron +
Vaccine escape variant
Omicron ++
© Oxera 2022
A study of the effectiveness of travel restrictions in the EEA
Oxera and Edge Health
11
Impact of delaying travel restrictions on the timing of the peak
—
As variants become more infectious according to the scenarios we have
modelled, it becomes more difficult to impose travel restrictions that
can have an impact on the timing of the peak of cases. The table below
shows how the delay of the peak depends on the number of days it takes
to put restrictions in place. For example, for Omicron +, if restrictions are
put in place one week after the variant is first imported, the peak would
be delayed by a maximum of two days. It took Italy over six weeks and
Finland eight weeks from the time that Omicron was first sequenced to
introduce travel restrictions.
The table below shows the impact of variant infectiousness on the delay of
the peak when travel volumes are high (i.e. 80% of 2019 levels). Variants
are ordered from least to most infectious. The scenario where Day 0 travel
restrictions are introduced can be considered akin to having pre-emptive
travel restrictions in place.
Day 0
4
4
2
2
Day 4
3
3
1
1
Day 2
3
3
1
1
Day 6
3
2
1
0
Day 1
4
3
2
1
Day 5
3
3
1
1
Day 3
3
3
1
1
Day 7
2
2
0
0
Omicron -
Omicron +
Vaccine escape variant
Omicron ++
Day restrictions are implemented
© Oxera 2022
A study of the effectiveness of travel restrictions in the EEA
Oxera and Edge Health
12
Conclusion
© Oxera 2022
A study of the effectiveness of travel restrictions in the EEA
Oxera and Edge Health
13
Conclusion
—
Air travel restrictions do not affect the size of the peak but could delay the
peak by a few days if they are introduced pre-emptively, or on the day that
the variant is first imported
Our analysis indicates that any travel restrictions imposed over the next
several months will have no impact on the size of the peak, but could
delay the peak of cases by a maximum of four days, regardless of the
level of passenger traffic. This is the case only if restrictions are imposed
pre-emptively, or could be introduced on the same day that a variant is
imported and therefore likely before it is actually identified as a VOC.
Any benefits of air travel restrictions diminish quickly over time
Each additional day of delay leads to a reduction in the effectiveness
of travel restrictions, such that if restrictions are not imposed until one
week after the variant is imported, there is at most two days’ benefit
to introducing such restrictions in terms of the trajectory of COVID-19
infections. In two of the scenarios considered, by Day 7 there will no longer
be any benefit to the restrictions and they should therefore be removed. It
is notable that it took countries such as Italy and Finland between six and
eight weeks from the time that Omicron was first sequenced to introduce
travel restrictions.
Ongoing restrictions will have a significant impact on the economy
Experience since the start of the pandemic indicates that it takes time to
become aware of a variant, and then to identify it as a concern, such that
putting policies in place sufficiently quickly is likely to be extremely difficult.
A potential alternative, therefore, would be to impose ongoing travel
restrictions in case a new variant emerges, potentially alongside local
restrictions. However, even in these cases restrictions will have minimal
benefits, and the significant direct and indirect costs to the economy would
need to be taken into account.
Monitoring the situation for the long term is important
In the longer term, if a less infectious variant is able to become dominant,
travel restrictions may have limited benefits. However, it is difficult to
determine potential scenarios beyond the short/medium term, and it would
therefore be important to reconsider the restrictions for the period beyond
the next several months at a later stage.
© Oxera 2022
A study of the effectiveness of travel restrictions in the EEA
Oxera and Edge Health
14
Appendix
© Oxera 2022
A study of the effectiveness of travel restrictions in the EEA
Oxera and Edge Health
15
A1.1
Sensitivity: when there is an ongoing vaccination roll-out
If there is an ongoing vaccine roll-out (e.g. due to waning immunity), travel
restrictions can have a small impact on the peak of cases and can delay
the peak by a few days, particularly when travel volumes are high.
Booster vaccine still being rolled out
Omicron +
Omicron +
No testing or quarantine
Pre-departure antigen 48hrs or PCR 72hrs
High volume
Low volume
Daily Omicron cases
Daily Omicron cases
40,000,000
30,000,000
20,000,000
10,000,000
0
40,000,000
30,000,000
20,000,000
10,000,000
0
Omicron ++
Omicron ++
Omicron -
(longer term)
Omicron -
(longer term)
Vaccine escape
variant
Vaccine escape
variant
© Oxera 2022
A study of the effectiveness of travel restrictions in the EEA
Oxera and Edge Health
16
However, as the variant gets more infectious, the impact of travel
restrictions on the delay in the peak decreases, even when boosters are
still being rolled out.
The table below shows the impact of variant infectiousness on the size
and delay of the peak when boosters are still being rolled out and travel
volumes are high (i.e. 80% of 2019 volumes). Variants are ordered from
least to most infectious.
Travel restriction
Pre-departure
antigen 48hrs or
PCR 72hrs
Delay in peak
relative to no testing
and quarantine
3
3
3
1
Reduction in peak
relative to no testing
and quarantine
2.3%
1.6%
0.3%
0%
Scenario
Omicron -
Omicron +
Vaccine escape
variant
Omicron ++
A1.2
Traffic sensitivity: traffic at 50% of 2019 levels
The table below displays the impact of variant infectiousness on the delay
of the peak when there are lower travel volumes (i.e. 50% of 2019 levels).
The variants are ordered from least to most infectious.
Boosters already
rolled out
Booster doses being
rolled out
Scenario
Omicron -
Omicron +
Vaccine escape
variant
Omicron ++
Omicron -
Omicron +
Vaccine escape
variant
Omicron ++
Time difference in
peak from no testing
and quarantine
4
4
3
2
4
4
3
2
Travel restriction
Pre-departure
antigen 48hrs or
PCR 72hrs
Pre-departure
antigen 48hrs or
PCR 72hrs
© Oxera 2022
A study of the effectiveness of travel restrictions in the EEA
Oxera and Edge Health
17
A1.3
Additional plots: impact of delayed implementation of testing
on timing of peak
A1.3.1
When there is no ongoing vaccination roll-out
Impact of introducing travel restrictions, by the delay from the day of the
first seeded case (pre-departure antigen 48hrs or PCR 72hrs)
Omicron
Omicron
0-day delay
1-day delay
2-day delay
3-day delay
4-day delay
5-day delay
6-day delay
7-day delay
8-day delay
9-day delay
10-day delay
11-day delay
12-day delay
13-day delay
14-day delay
No testing/quarantine
High volume
Low volume
Daily Omicron cases
Daily Omicron cases
20,000,000
15,000,000
10,000,000
5,000,000
0
20,000,000
15,000,000
10,000,000
5,000,000
0
Omicron ++
Omicron ++
Omicron -
(longer term)
Omicron -
(longer term)
Vaccine escape
variant
Vaccine escape
variant
© Oxera 2022
A study of the effectiveness of travel restrictions in the EEA
Oxera and Edge Health
18
A1.3.2
When there is an ongoing vaccination roll-out
Impact of introducing travel restrictions, by the delay from the day of the
first seeded case (pre-departure antigen 48hrs or PCR 72hrs)
Omicron +
Omicron +
0-day delay
1-day delay
2-day delay
3-day delay
4-day delay
5-day delay
6-day delay
7-day delay
8-day delay
9-day delay
10-day delay
11-day delay
12-day delay
13-day delay
14-day delay
No testing/quarantine
High volume
Low volume
Daily omicron cases
Daily omicron cases
40,000,000
30,000,000
20,000,000
10,000,000
0
40,000,000
30,000,000
20,000,000
10,000,000
0
Omicron ++
Omicron ++
Omicron -
(longer term)
Omicron -
(longer term)
Vaccine escape
variant
Vaccine escape
variant
© Oxera 2022
A study of the effectiveness of travel restrictions in the EEA
Oxera and Edge Health
19
A1.4
Assumptions
A1.4.1
Assumptions on travel volumes and air passenger prevalence
Model input
Median infectious days an
air passenger spends in their
destination
Air passenger volumes
Air passenger COVID-19
prevalence
Percentage of positive cases
attributed to other variants
Value
3 days
We model two
scenarios: 50% of
2019/20 volumes
and 80% of 2019/20
volumes.
Prevalence:
1.1–1.2%
Source
Oxera and Edge Health (2021),
‘Effectiveness of dual-testing
schemes for air passengers’.
For LSHTM’s work see:
Clifford et al. (2020), ‘Strategies
to reduce the risk of SARS-
CoV-2 re-introduction from
international travellers’, 25 July.
IATA
https://www.gov.uk/government/
publications/weekly-statistics-
for-nhs-test-and-trace-england-
2-to-8-december-2021
https://www.bancaditalia.
it/pubblicazioni/indagine-
turismo-internazionale/2021-
indagine-turismo-internazionale/
statistiche_ITI_18062021.pdf
https://www.finavia.fi/en/about-
finavia/about-air-traffic/traffic-
statistics/traffic-statistics-year
https://www.ecdc.europa.eu/
en/covid-19/situation-updates/
variants-dashboard
Description
Without quarantine and testing schemes,
when a passenger is infected in another
country, they will spend some of their
infectious days in their country of departure
and some in their country of arrival. Using
a simulation model based on a paper from
the London School of Hygiene & Tropical
Medicine (LSHTM), we estimate the median
number of infectious days a passenger will
spend in their country of arrival to be 3.
We use IATA data on passenger volumes
from outside to inside the EEA for
February–June to approximate future air
traffic volumes. We model two scenarios:
50% of 2019/20 volumes and 80% of
2019/20 volumes. We assume that most
passengers are completing round trips, so
passenger volumes are divided by two to
get inbound passengers.
To recreate future fictional scenarios
that are comparable to Omicron, we
model future VOCs (Omicron -, Omicron
+, Omicron ++, and the vaccine escape
variant) assuming that the prevalence is
the same as Omicron was towards the
beginning of the wave.
Omicron assumptions: we use UK
government Test and Trace data available
up to 13 December to approximate potential
future air passenger prevalence, scaling for
historical tourism numbers across several
European countries. We conservatively
use Germany, with the highest estimated
incoming air passenger prevalence.
Omicron -, Omicron +, Omicron ++ and the
vaccine escape variant are assumed to be
the same as Omicron in proportion of total
positive cases in air passengers towards
the beginning of the wave.
Omicron assumptions: the percentage
shares of Omicron cases are based on the
European average from the ‘SARS-CoV-2
variants dashboard’ disclosed by the
European Centre for Disease Prevention
and Control (ECDC).
–
© Oxera 2022
A study of the effectiveness of travel restrictions in the EEA
Oxera and Edge Health
20
A1.4.2
Assumptions on travel testing efficacy
Model input
Antigen 48hrs pre-departure or
PCR 72hrs before departure
No testing or quarantine
Value
46%
–
Source
Oxera and Edge Health (2021),
‘Assessment of the effectiveness
of rapid testing for SARS-CoV-2’.
Oxera and Edge Health (2021),
‘Effectiveness of dual-testing
schemes for air passengers’.
Description
We use the efficacy of pre-departure testing
at screening incoming air passenger
infectious days as a model input. We use
the estimated efficacy of antigen and PCR
tests taken at the respective times pre-
departure, taking the weighted average
assuming that two-thirds of passengers will
opt for the cheaper antigen test option.
Assuming that no testing or quarantine
schemes are used to screen incoming air
passenger infectious days.
Assuming that no testing or quarantine
schemes are used to screen incoming air
passenger infectious days.
A1.4.3
Assumptions on EEA booster vaccine roll-out
Model input
Historical vaccination rates
Projected vaccination rates
Value
–
–
Source
https://www.ecdc.europa.eu/en/
publications-data/data-covid-19-
vaccination-eu-eea
https://www.ecdc.europa.eu/en/
publications-data/data-covid-19-
vaccination-eu-eea
Description
We use weekly vaccination data for the EEA
as published by the ECDC, and estimate
daily vaccination uptake by aggregating
reported numbers of administered first,
second and third doses by countries, target
groups and vaccine manufacturers.
We calculate the average daily vaccinations
delivered in the last week of available data
to estimate the speed of the vaccination
roll-out in projected scenarios. We assume
that the number of individuals receiving a
second dose cannot exceed the number
of individuals who had received a first
dose three months prior. This is based
on medical recommendations to get
second doses within three months of the
previous dose. Equally, we assume that
the number of individuals receiving a third
dose (booster) cannot exceed the number
of individuals who have received a second
dose. As the speed of vaccination roll-out is
dose-specific, to prevent a violation of the
assumption above in the later stages of the
projection, the speed of roll-out for a dose is
set to the speed of the dose of the lower tier
where required.
© Oxera 2022
A study of the effectiveness of travel restrictions in the EEA
Oxera and Edge Health
21
A1.4.4
SARS-Cov-2 and variant-specific parameters (I)
Model input
Ro
Days infectious
Incubation period
Impact of natural immunity (for
people previously infected with
the Omicron variant)
Natural immunity for new
variants compared to Omicron
Value
Omicron +: 9.14
Omicron ++: 18.28
Vaccine escape
variant: 8
Omicron -: 8.68
Omicron: 8,
assuming that Delta
has an Ro of ~3.2
(this assumes pre-
pandemic mixing
patterns)
7.35 days
3 days
84% decrease in
risk of infection,
immune escape of
16%
50%
Source
https://www.medrxiv.org/
content/10.1101/2021.12.19.
21268038v1.full.pdf
https://assets.publishing.
service.gov.uk/government/
uploads/system/uploads/
attachment_data/
file/1043466/20211222_OS_
Daily_Omicron_Overview.pdf
https://github.com/blab/rt-
from-frequency-dynamics/tree/
master/estimates/omicron-
countries
Ro of Delta: https://academic.
oup.com/jtm/article/28/7/
taab124/6346388
Oxera and Edge Health (2021)
‘Effectiveness of dual-testing
schemes for air passengers’.
For LSHTM’s work see: Clifford
et al. (2020), ‘Strategies to
reduce the risk of SARS-
CoV-2 re-introduction from
international travellers’, 25 July.
https://www.eurosurveillance.
org/content/10.2807/1560-7917.
ES.2021.26.50.2101147
https://www.sciencedirect.
com/science/article/pii/
S0140673621006759?casa_
token=d-Aupl8roEYAAAAA:E_
YnW1p75HlEH7DgPN_N_7aCA
No7QcSrk93TlvcAS2khOBLt6r
CwhCpwh8eYPh-bMGIscQ6k
https://www.imperial.ac.uk/
media/imperial-college/
medicine/mrc-gida/2021-12-16-
COVID19-Report-48.pdf
Description
We assume that Omicron + and
Omicron ++ are 1.25 and 2.5 times,
respectively, more infectious than Omicron,
once 20% of the population has been
infected with Omicron and therefore has
some form of natural immunity. The Vaccine
escape variant is equally as infectious
as Omicron. The Omicron - variant is
1.25 times as infectious as Omicron once
25% of the population has been infected.
These factors combine in our model to
result in a calculated Rt. Initial Omicron
assumptions: initial data suggests that
the Rt and secondary attack rates of the
Omicron variant are 2 to 3 times higher than
those of the Delta variant. While some of
this difference is likely to be due to differing
immunity for the variants in the population,
we conservatively assume that Omicron is
2.5 times more infectious than Delta.
As reports of the duration of the infectious
period for the Omicron variant are not
available at the time of writing, we use
the median time an individual is infectious
calculated from previous variants.
Preliminary evidence suggests that the
time from exposure to symptoms is shorter
for the Omicron variant compared to other
variants.
Studies conducted in England suggest that
a previous history of infection reduces the
risk of re-infection by 84%. Infections with
previous variants were protective against
infection with the Alpha variant. Immunity
was observed for a minimum of seven
months after initial infection. We assume
that the immunity for the Omicron variant
is similar, and apply scaling based on
estimates of the relative efficacy of vaccines
to the Omicron and Delta variants.
Natural immunity for the Omicron -,
Omicron +, Omicron ++ and the Vaccine
escape variants is assumed to be the
same as for Omicron. We estimate this
using the relative efficacy (for vaccinated
individuals with two or three doses) against
the Omicron variant compared to the Delta
variant, using a weighted average of the
Pfizer +Pfizer and AZ + Pfizer combination.
© Oxera 2022
A study of the effectiveness of travel restrictions in the EEA
Oxera and Edge Health
22
A1.4.4
SARS-Cov-2 and variant-specific parameters (II)
A1.4.5
Impact of local social distancing measures on infection spread in
the EEA, assuming that some mask/testing requirements
continue
Model input
Unvaccinated population who
have previously been infected
Delay between vaccination and
vaccine efficacy
Estimated relative efficacy
of vaccinations against new
variants, based on data from
Omicron
Model input
Impact of mandatory masks,
symptomatic testing
Value
20% (short/medium
term) or 25% (longer
term)
Step function,
1 week
See Table 1, p. 14
Value
-17.9%
Source
https://www.ecdc.europa.eu/en/
publications-data/data-daily-
new-cases-covid-19-eueea-
country
http://www.bccdc.ca/
Health-Info-Site/Documents/
COVID-19_vaccine/Public_
health_statement_deferred_
second_dose.pdf
https://www.imperial.ac.uk/
media/imperial-college/
medicine/mrc-gida/2021-12-
16-COVID19-Report-48.pdf
and https://assets.publishing.
service.gov.uk/government/
uploads/system/uploads/
attachment_data/file/1043807/
technical-briefing-33.pdf for
real-world supplementary data.
https://cmmid.github.io/topics/
covid19/reports/omicron_
england/report_11_dec_2021.
pdf
Source
https://www.medrxiv.org/
content/10.1101/2020.05.28.2011
6129v4.full.pdf
http://epidemicforecasting.org/
containment-calculator
https://bmcmedicine.
biomedcentral.com/
articles/10.1186/s12916-020-
01872-8/figures/5
Description
We use data on EEA cases beginning in
the month of November (mainly Omicron)
to project how many of the unvaccinated
population will have natural immunity to
Omicron by May/July.
While immunity builds up over time after
individuals are vaccinated, there is still
substantial protection from vaccinations
(~60%) on the first day after vaccination.
Using a step function, we are able to
approximate this effect.
Vaccine efficacy for Omicron -, Omicron +,
Omicron ++ are assumed to be the same as
for Omicron. The vaccine efficacy against
the Vaccine escape variant is assumed to
be half of Omicron.
Modelling from Imperial has estimated
the relative efficacy of vaccinations
against the Omicron variant, extrapolating
laboratory studies to real-world efficacy.
We supplement this with data on real-world
efficacy, which is now starting to become
available.
These estimates are conservative
compared to the range of scenarios
estimated by other modelling groups
(LSHTM).
We also assume, given recent data
on Omicron hospitalisation rates, that
vaccines remain similarly protective against
hospitalisation or death to Delta.
Description
The reduction in Rt resulting from
non-pharmaceutical interventions.
© Oxera 2022
A study of the effectiveness of travel restrictions in the EEA
Oxera and Edge Health
23
Contact:
Michele Granatstein
Partner, Oxera
[email protected]
+44 (0) 20 7776 6606
Jennifer Connolly
Data Scientist, Edge Health
[email protected]
+ 44 (0) 20 8133 4504
George Batchelor
Co-Founder and Director,
Edge Health
[email protected]
+ 44 (0) 20 8133 4504
www.oxera.com