Can closing borders shut out new COVID-19 strains?

by Jayant Menon

Travelers at the airport | Photo via Asia Pathways

Jayant Menon

In fighting the coronavirus disease (COVID-19) pandemic and, in particular, the new strains that are emerging, many countries have adopted the dual approach of closing borders and increasing domestic surveillance. This might be overkill. In fact, the latter might suffice.

Since COVID-19 was first detected in human beings just over a year ago, it has undergone several thousand mutations. The mutations were ignored because they did not appear to alter transmissibility or virulence. This changed in December 2020, when a spike in infections in the United Kingdom (UK) was finally linked to a variant called B.1.1.7, and then another surge in South Africa to one called 1.135. With the emergence of yet another variant, P.1 from Brazil, there is growing concern that most recent surges worldwide could be due to new variants, some still unidentified.

These fears have led some countries to ban travelers from countries where the new strains have been reported. Can such selective travel bans prevent or limit the entry of the new strains? The evidence suggests that they cannot and that there are better ways to limit the spread.

The main reason why the bans cannot prevent the entry of the new strains has to do with the nature of the identification process. It is difficult to determine from the genetic sequencing alone whether the variant will be more transmissible or virulent, and so it needs to show up in large case numbers before this can be determined. This is why it took until 14 December 2020 before UK authorities raised the alarm over a strain they discovered in September, although it may have emerged as early as March. Governments are reluctant to change policy until there is evidence of increased transmissibility or virulence, and by then it is usually too late. In this case, the UK strain had already spread to about 50 countries. The number of countries continues to increase because not all are able to test with equal efficiency or speed. These differences in genomic surveillance capacity further highlight the futility of trying to keep the new strains out through selective travel bans. Since we cannot be sure where the new strains have spread to, a ban on all travelers would be required, assuming borders were not porous. Even if a complete ban could be enforced, it would be economically unsustainable.

“The main reason why the bans cannot prevent the entry of the new strains has to do with the nature of the identification process. It is difficult to determine from the genetic sequencing alone whether the variant will be more transmissible or virulent, and so it needs to show up in large case numbers before this can be determined.”

There are better and less costly ways of controlling the new strains. If domestic protocols involving testing, quarantine, and tracing are applied effectively, then they would provide the best chance of limiting the local spread of the original and new strains.

Singapore and Zealand, two countries lauded for their pandemic response, demonstrate how this approach can work. Although recent daily imported cases in Singapore have been in the double-digits, with a cumulative total in the thousands, this has not resulted in a direct case of community transmission because of effective domestic protocols. New Zealand confirmed its first case of local transmission in several months on 25 January, and it was the South African variant. It occurred because a breach in quarantine tells us that no system is perfect and can always be improved. But other domestic protocols, including rapid testing and efficient tracing, kicked in to prevent the quarantine breach from turning into a community outbreak. And when three cases of the UK variant were detected on 15 February in Auckland’s capital city, a snap 3-day citywide lockdown and enhanced domestic surveillance measures again prevented a larger outbreak. New Zealand and Singapore have selective travel bans and borders that can be effectively policed and monitored. Despite this, both countries have reported new variants within their borders, confirming that short of total isolation, importation of the virus is almost inevitable. These countries also have lower community transmission rates, reducing the risk of an indigenous mutation. Therefore, it is the efficient implementation of domestic protocols rather than selective travel bans that ultimately provide protection.

While it is and has always been too late to close borders, why do governments insist on them? There has been a bias against the easing of restrictions at the border compared to measures curtailing domestic movement even when dealing with the original strain. The emergence of the new strains seems to have reinforced this bias. It may be that governments want to appear to be responding directly and decisively to the new threat. Pretending that they can repel the threat at the border itself could be electorally appealing. It may also give the impression that the costs are borne by non-residents when the domestic economy suffers. Finally, when the measure inevitably fails, governments can always find scapegoats while claiming to have tried their best rather than admit to having botched their response.

“The solution, however, still lies with a speedy rollout of mass vaccination campaigns. The race is no longer just between vaccine rollout and community spread but also against the emergence of ever more resistant strains. Improved domestic surveillance, rather than border closures, is needed to buy time for the vaccine rollout, delayed by bureaucracy and nationalism if we are to defeat a rapidly mutating virus.”

In sum, just as it was with the original strain, closing borders will not stop the new or future variants from finding their way in. The evidence suggests that countries that can efficiently implement domestic surveillance manage the original and new strains better, with the additional protection from selective travel bans likely to be low or redundant. For countries with weak domestic surveillance capacity or lax domestic protocols, travel bans’ marginal value is higher but diminishes rapidly as new strains spread indiscernibly to more countries. Improving domestic protocols or surveillance will be less costly and more effective than continuously increasing or prolonging border restrictions.

The solution, however, still lies with a speedy rollout of mass vaccination campaigns. The race is no longer just between vaccine rollout and community spread but also against the emergence of ever more resistant strains. Improved domestic surveillance, rather than border closures, is needed to buy time for the vaccine rollout, delayed by bureaucracy and nationalism if we are to defeat a rapidly mutating virus.


ABOUT THE AUTHOR: Jayant Menon is a visiting senior fellow at the ISEAS–Yusof Ishak Institute, Singapore. This article first appeared at Asia Pathways – the blog of the Asian Development Bank Institute.

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