Messaging from the CDC and health departments throughout the pandemic have consistently underscored the importance of avoiding travel due to the very nature of travel increasing exposure to others, in turn increasing one’s risk of becoming infected, having an adverse health outcome, and also increasing the risk of spreading COVID-19 to others both during and for some time after returning.
In the context of rising numbers of diagnosed cases, hospitalizations, deaths, and overwhelmed healthcare systems, the argument to refrain from unnecessary travel had been clear. But as we see the fall in case numbers, the data on effectiveness of interventions such as masks and distancing, the distribution of highly effective vaccines, and the economic and psychological impact of lockdowns, the hope and desire to relax travel restrictions is becoming more apparent.
The fire hose of new information continues to inundate the medical, scientific, and public health communities. It is often hard to stay updated on all the latest studies that could inform major decisions and policies.
Even when presented with the same information, expert opinions on what is “safe” and what is “ethical” regarding issues such as dining, schools, mass gatherings, and travel are as nuanced as the projections of what the pandemic will look like in the coming months.
Let’s look at what the data reveals on some of the key factors that come into play.
Vaccination
Little argument can be made against the astonishing efficacy of COVID-19 vaccines in protecting individuals against illness and death. According to the phase III clinical trials, Pfizer’s COVID-19 vaccine reduced the risk of getting ill from COVID-19 by 95%, Moderna’s by 94.5%, Johnson & Johnson’s by 66%, and AstraZeneca’s by approximately 70%.
In the U.K., the Public Health England found that one dose of the Pfizer vaccine reduced the risk of infection among healthcare workers under 65 years old by 72% at 3 weeks. Based on this data, many experts advocate for a national strategy that includes postponing the second dose of vaccine in order to more widely distribute first doses across the country (and globe) sooner, particularly as the concern about variants arise.
While these efficacy rates are encouraging for the individual who is vaccinated, the less understood but important variable in deciding the safety and ethics of travel goes beyond the individual’s protection and on to how effective vaccines are in preventing a person from transmitting COVID-19 to others.
Further data is needed to truly understand just how much reduction in transmission is offered by vaccines, but the medical community is very optimistic that the amount of reduction will be impressive and considerable.
How protective these vaccines are and will be against emerging variants is also still largely unknown. Given the error-prone nature of the replication machinery of SARS-CoV-2, as well as its capacity to mutate under immune pressure, as spread continues so does the chance that more variants will arise.
Therefore, the high level of vaccine efficacy against both illness and transmission can be applied to that specific variant. Vaccine manufacturers are studying how well vaccines perform against all variants of concern in the laboratory setting as well.
While the level of neutralizing antibody against some variants has been shown to be reduced, many agree that there is likely still considerable protection in the real world given the baseline high level of efficacy and the additional role that T and B cells play in immunity, which is not easily measured in the laboratory.
Other variants of concern are circulating worldwide, including ones that have increased transmissibility, potential to cause more severe illness, death, and reduced efficacy to the currently available vaccines. In response to this, the FDA has stated that modifications to previously authorized vaccines may be authorized without the need for further lengthy clinical trials.
While we don’t fully know when “herd immunity” will be reached, most estimate this to be when 70%-80% of the population is considered immune.
With the rate of re-infection within 90 days of recovery from COVID-19 being so low, the CDC does not recommend quarantine for exposures within that timeframe. And given the data known so far, the CDC also does not recommend quarantine after an exposure for those who have been fully vaccinated and have had time to develop full protection (i.e., more than 2 weeks from their second dose).
So, for a traveler who is immune either by being fully vaccinated or having recently recovered from COVID-19, herd immunity at a given destination and within their home community is less of a variable, both in terms of risk of illness and risk of transmitting virus to others. Add on behavioral methods proven to substantially reduce one’s risk and viral transmission (fitted masks, social distancing, outdoors over indoors, etc.) and one can feel good about traveling responsibly.
