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In case useful, here are some general comments about travel restrictions and COVID-19 following an update to the UK’s foreign travel ‘traffic light’ lists.
Dr Peter English, Retired Consultant in Communicable Disease Control, Former Editor of Vaccines in Practice, Immediate past Chair of the BMA Public Health Medicine Committee, said:
“Some countries have decided to relax travel restrictions for people who are fully vaccinated against Covid-19; and others have done it for people returning from countries where there are not variants of concern. (Sadly, for us in the UK, the Delta variant is considered a variant of concern, so travel to Germany, for example, is restricted from the UK, even for fully vaccinated individuals.)
“There is much discussion about whether such relaxations are safe or not.
“Epidemiologists and other scientists tend to be very uncomfortable about binary “safe/not safe” categorisations. There is always a scale, and a degree of risk; things are very seldom totally safe. So what would need to be considered is two questions: what level of risk would there be from relaxing restrictions for people who are fully vaccinated?; and what level of risk are we prepared to accept?
“We do know that Covid-19 vaccination, particularly after two doses, is effective at preventing disease. And we know that it is most effective at preventing serious disease, hospitalisation, critical care admissions, and deaths. Vaccination is also moderately effective at preventing asymptomatic infection; although this is harder to assess.
“And we are less clear about how effectively vaccination prevents people from being infected and infectious to others; although there some evidence that the less ill people are, the less infectious they are (although it is also clear that asymptomatic people can be infectious, so this is a matter of degree, rather than binary).
“Given that vaccination is only moderately effective at preventing infection, and we are unclear about how effective it is at preventing infection and infectiousness (causing disease in others), relaxing all restrictions for people who have been fully vaccinated would clearly not eliminate the risk. But would it reduce it sufficiently? Well, that depends on what level of risk you are prepared to accept.
“At the moment, the science can tell you that the risk to others from fully vaccinated people returning from places with a moderate to high prevalence of Covid-19 (and possibly of moderate to high prevalence of variants of concern) will be considerably lower than for people who are not at all vaccinated, and lower than for those or are not fully vaccinated, but it is unclear precisely how low the risk will be. (And of course, it will be highly dependent on the prevalence where they are returning from, and the risks they took while they were there – such as travelling on trains without a mask.)
“I hope very much that vaccines will turn out be highly effective at preventing people from becoming infected and infecting others; but I’m very glad that politicians, not scientists, will have to make the judgement as to whether it is “safe enough” to allow fully vaccinated people to return to the country from places where Covid-19 (especially variants of concern) are circulating widely, without the requirement for quarantine and/or testing on return.
“Because the risk to people who are fully vaccinated is so low, I would be comfortable for restrictions to be lifted in contexts where everybody is known to be fully vaccinated.”
Comment transcribed from a video that was recorded before the latest travel guidance was issued last night:
Prof Neil Ferguson, Director of the MRC Centre for Global Infectious Disease Analysis, Imperial College London, said:
“The effectiveness of two doses of vaccine preventing infection is, depending on the vaccine, we think somewhere between 80 and 90%. Even if you do get infected, first of all, you’re much less likely to be severely ill, but you’re also, and this is important for travel, much less likely to transmit, probably half as infectious as someone who wasn’t vaccinated. Overall, that leads to doubly-vaccinated people really only posing somewhere between 5 and 10% of the risk of importing a case than someone who wasn’t vaccinated. In the sense that we are balancing risks versus benefits here, I think it’s a sensible approach to move to loosening restrictions if people have had two vaccine doses.”
Watch the full (2 minute) video with Prof Neil Ferguson, which is where this quote was taken from: https://twitter.com/MRC_Outbreak/status/1408328891438149633
Comment sent out before the latest travel guidance was issued last night:
Prof Paul Hunter, Professor in Medicine, UEA, said:
“Once again, the appropriateness or otherwise of current border restrictions in protecting the UK population from the COVID pandemic is being debated in national media and the scientific basis for the current rules is being questioned.
“Border controls such as screening on entry and departure, quarantines and border closures have a long history in the attempted control of the spread of infectious disease and, in general, they have not done well. Rarely have border controls prevented the spread of an infectious disease, though they have been shown to delay spread. In a systematic review of the evidence on influenza, published in 2014, Mateus and colleagues concluded that “Extensive travel restrictions may delay the dissemination of influenza but cannot prevent it. The evidence does not support travel restrictions as an isolated intervention for the rapid containment of influenza. Travel restrictions would make an extremely limited contribution to any policy for rapid containment of influenza at source during the first emergence of a pandemic virus”1. They also found that for travel restrictions to be effective they have to be implemented quite early in a pandemic and were rather less effective when the level of transmission was high.
“Also pre-dating COVID another group reviewed the evidence for screening for infectious diseases at borders and concluded that screening was generally ineffective2.
“So the evidence prior to 2020 is that border controls effectively only delay and not prevent the inevitable. At some point restrictions have to be lifted and unless other measures have been put in place the epidemic then still spreads through the country anyway.
“Looking at evidence from the current pandemic an international consortium of scientists effective came to the same conclusions about the relative lack of impact of travel restrictions unless very strict and combined with tight restrictions within country3.
“But sometimes a delay in spread may be sufficient as when a vaccine campaign is underway that will soon lead to the protection of a large proportion of the population. The current epidemic of the delta variant in the UK was driven in its early stages by the importation of hundreds and possibly thousands of infections from India. Without that rapid influx of cases early on, the current state of the epidemic in the UK would look quite different and it is doubtful that step 4 of the lockdown easing would have had to have been delayed. In this context delaying the inevitable would likely have had real benefits.
“But where does that leave us today? At present the UK has the highest rate of infection in western Europe and almost all of our cases are the Delta variant. So, at the moment a British person spending time in Europe would be less at risk of exposure to an infected person than whilst doing the same types of activities in the UK. Although the Delta virus has spread to several European countries, most notably Belgium, France, Germany, Portugal and Spain it is not yet the dominant variant, though as pointed out by the European Centres of Disease Control it will not be long before the Delta variant does become dominant throughout Europe.
“Added to this the benefit of the very successful vaccination campaign in the UK and it is difficult not to conclude that travel at least to European countries does not pose an important additional risk above that of travel in the UK. In my view the benefits of current travel and border restrictions, at least to Europe, are reaching their end. But if relaxing all such restrictions is felt to be a step too far then allowing people with two doses of vaccine to travel would be a compromise and would reduce the risk of importation even further.”
All our previous output on this subject can be seen at this weblink:
www.sciencemediacentre.org/tag/covid-19
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