Dr. David L. Heymann, Professor, London School of Hygiene and Tropical Medicine talks to Tony Concil about the latest developments in the pandemic and the prospect of restriction-free travel

What can we expect in 2022?

Many countries have begun now to treat COVID-19 as an endemic disease with control programs. For example, in August last year the UK began to shift the responsibility of risk assessment and risk management to individuals. People were provided with free self-testing equipment and the knowledge to manage risks. Today, people are managing their risks by measures like self-testing before they go out to visit elderly grandparents, for example. And there are many other things they are able to control within their own capacity.

This is different from what happened previously, when the UK government was making its own risk assessment and then using blunt tools like lockdowns or stopping travel at borders to try to prevent the rapid entry of the virus.

And the UK is not alone. Many countries are shifting the risk assessment and risk management from the government to individuals. And the government’s focus then becomes surveillance and response capacity. This is how seasonal influenza is managed—collecting and genetically sequencing virus specimens from persons with influenza-like illness to understand how variants are evolving. In parallel, the government has stepped up its capacity to investigate outbreaks to identify the source of transmission and to then lockdown precisely where transmission is occurring—a night spot, for example.

What is enabling the UK to make this shift?

Population immunity. Over 98% of the UK population is thought to have antibodies for COVID-19. That comes from vaccination, natural infection, or a combination of both. From a public health perspective, it is a very strong number. And other countries will be watching closely to see the results of this management strategy—treating COVID-19 as an endemic virus with occasional surges in transmission as occurs with influenza.

Is the UK’s strong population immunity a result of its experience with Omicron? And what can we expect from future variants?

Viruses produce variants. That is why surveillance is so important and we cannot let our guard down on that.

The Omicron variant has changed many parameters. For example, there is a shift taking place in tracking. Governments are now focusing more on hospital admissions, intensive care occupancy, and deaths rather than on new cases. I don’t expect that we will have a great announcement one day that the pandemic is over. But this shift in focus is an indication that we are moving towards the endemic phase where policy is built on the assumption that this disease will be with us long term and that we must learn to live with it.

Learning to live with it means that we won’t have more border closures?

A border closure early in the pandemic may give a country some days or maybe even weeks to prepare. But that is all. The travel bans that followed the discovery of Omicron did not contain its spread. That is because by the time it was identified, it was already present in many places. Countries recognized this and most of them rapidly lifted the bans.

If travel bans are not effective, what could governments do to stop people from spreading the virus in their countries?

If countries really want to determine whether people are carrying a virus, they can require a rapid diagnostic test on arrival. But even that will miss cases because there's a period in infection when the virus cannot be detected either by PCR or by lateral flow test. Now is the time to ramp up surveillance activities—the method we use to understand other endemic diseases, including the evolution of new variants.

How about requiring that travelers are vaccinated?

Vaccination against COVID-19 is an individual protection measure, not a public health measure. That is different from vaccination for other infections, such as measles, which prevents infection. The COVID-19 vaccines we have at present do not prevent infection in all instances, but they do prevent infections that occur after vaccination from causing serious illness and death in the majority of people.

If people are required to have a COVID-19 vaccination before travel, one rationale may be that countries requiring vaccination don't want travelers to come to their country and develop serious illness or die. Another rationale may be that because those who are vaccinated and become infected have less virus in their nasal passages, they are therefore at less risk of spreading infection to others. Countries, of course, are fully within their rights to require this. But it is important that we all understand that vaccination for COVID-19 builds population immunity to protect people from serious illness and death if they are infected after vaccination. Current vaccines do not provide herd immunity that could stop transmission.

Are countries that have kept their borders closed and kept COVID-19 infection numbers low likely to have a lower population immunity and be slower to re-open their borders?

Countries like Australia and New Zealand were closed for much of the pandemic—with severe lockdowns. They are now planning to re-open, likely because they feel they have a high enough vaccination coverage, including in people who are at great risk of serious illness and death. At-risk groups include those who are obese, have diabetes or other conditions, as well as the elderly and those with compromised immune systems. The ways and times that countries change policies and strategies depend to a great extent on the risk the government is willing to take.

Important now is how the virus enters countries that are emerging from lockdown in a slow and controlled manner so that it doesn't overwhelm their health systems. And those persons who aren't vaccinated or who don’t have immunity through prior infection are those at greatest risk of serious illness.

Every country seems to have different rules for vaccinations. They recognize different periods of validity, different kinds of vaccines, and varying age groups. What mechanism is there among countries to achieve a common standard that would simplify travel?

The World Health Organization (WHO) is the logical place where countries should be working together, under the International Health Regulations, to normalize circulation of people and goods internationally. That has not occurred. Countries have preferred to develop their own strategies based on their own risk assessments. Countries have the sovereign right to do this.

But that does not eliminate the need for a common approach.  And hopefully, in the future, there will be a mechanism within the WHO that countries will feel is useful. Normalizing international travel is important and that will benefit from greater standardization than we have today.

Can we expect COVID-19 to become like the flu? And is it reasonable to manage it as we do the flu?

That is an impossible question to answer. Mutations will occur. And it is possible that a mutation could lead to vaccine escape and more serious illness after infection. But nobody can predict.

We can, however, look at the four endemic human coronaviruses, which have also come from the animal kingdom. Over time, population immunity developed, and these viruses have settled into a more routine way of infecting humans. They likely cause less serious illness now than when they first entered human populations. Today, they cause the common cold.

Our hope would be that COVID-19 will do the same. But, at present, we don't know, and we can't predict.

What we do know is that coronaviruses mutate. To keep vaccines effective, they may need to be regularly updated. Influenza vaccines must be updated each year because of the variants that develop during each seasonal epidemic and the period between epidemics. That is why we have a global network of laboratories providing information from genetic sequencing of the influenza virus to the WHO and on to vaccine manufacturers so that the best possible vaccines can be developed each year. That may be the same pattern we have to follow for COVID-19. We don't have to do that for the four endemic coronaviruses that cause the common cold. There is no vaccine for these infections, but reinfection with these viruses can occur after a period of six months or more, and fortunately these coronaviruses do not disrupt our daily lives.

With so much uncertainty, what should policymakers be focusing on?

We have known clearly since the SARS outbreak in 2003, and much before that, that border closures or restrictions do not protect against the entry of infectious diseases. What's most important is for countries to have in place systems that detect and can rapidly respond to infections when and where they occur in the country. That moves the focus from borders to national systems. And it puts the emphasis on surveillance.

Governments are also using testing on arrival or on departure as an entry requirement. Is that going to be a long-term feature of travel? And what kind of testing can we expect?

Whether or not testing will required in the future is not clear. But efficient testing systems may be useful if there's another pandemic or if a future variant is linked to more serious illness.

The variety of testing methods is growing. Many are already familiar with rapid lateral flow testing, which is a more cost-effective and faster option than PCR testing. So, it is better suited to facilitate travel.

There has been much money spent by governments and individuals on testing for travel during the pandemic. Recently, there has been a rationalization in most countries with fewer countries requiring testing. That is particularly true for vaccinated people traveling internationally.

That is the case in the UK, where its surveillance system is among the best in the world. The UK did away with post-arrival testing and will rely on surveillance to detect any outbreaks and importantly any new variants that may be circulating.

Will we ever travel as we did in 2019?

Travel will begin to normalize as governments accept that this virus is not going to disappear and move towards public health policies that treat it as an endemic condition. That means having measures in place to do effective surveillance and rapid response. And they will want to be sure that their population understands how to deal with infection. Provided those conditions are met and there are no new variants of concern emerging that cause a decrease in protection against serious illness, there's no apparent reason that travel can't return to normal within the coming year.

What about mask-wearing?

Mask-wearing has helped protect people from passing COVID-19 infection to others. And we have not seen the normal seasonal surge in influenza during the pandemic—which could at least be partly attributed to mask-wearing. Masks are being shown to be a good public health tool.

When we reach the point where mask-wearing is no longer required, people may decide themselves whether or not they wish to wear a mask. If they feel an obligation to protect others, they may choose to wear a mask if they feel sick or are in proximity to those who are vulnerable. This was already a habit in many parts of Asia even prior to the pandemic.

What are the implications of Long COVID?

Long COVID is a big caveat to this discussion. We don’t understand this phenomenon that is occurring in many people who were infected. And there is work underway to understand long COVID better, including the impacts of the lockdown, such as its psychiatric and psychological effects.

Research will eventually give us a clearer picture. At this stage even if the immediate effects of infection are mild, the unknown long-term impacts of Long COVID make it unwise to build population immunity by simply letting the virus infect everybody in a country. We must remember the importance of vaccination and the good fortune to have vaccines so rapidly—and there is some evidence that there is less Long COVID reported among those who become infected after vaccination.

What do you think we've learned from this pandemic?

This pandemic has highlighted three key areas for preparedness. One is that countries require strong public health systems that can detect and respond to infections when and where they occur. The second is that they require a surge capacity and resilience in the health system to accommodate people who might be infected during a pandemic without having to cut normal services. And the third is that preparedness requires a population that is in good health. We've seen that people who are healthy can fight infection better than people with comorbidities like obesity and diabetes.

Strong public health, resilient health systems, and healthy populations must be the baseline for all governments to prepare for future pandemics. And, of course, addressing a pandemic needs a whole-of-government approach so that the potential for and consequences of economic damage resulting from public health measures is also considered.

And for the airline industry?

My suggestion is that the airline industry figures out a way to work more closely with governments so that it is contributing to government risk assessment and risk management discussions in a way that does not create a real or perceived conflict of interest. This may not be easy but hearing the views of the industry has the potential to make an important contribution.

When we spoke a year ago, you said that you were looking forward to getting back to traveling. May I ask what your experience was like?

I've had no trouble traveling internationally by making myself aware of the rules and following them. I've been to the United States from the UK. I've been back and forth between Geneva and the UK. And there's been no difficulty in that travel. Even if I don’t agree with the necessity of all the measures in place, I adhered to them and was able to get to where I needed to be without difficulty. But, of course, like everyone, I am looking forward to future travel with fewer measures to contend with!


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