British report suggests variants may challenge COVID-19 pandemic strategies

Linda Lew, South China Morning Post

Posted at Aug 12 2021 01:53 PM | Updated as of Aug 12 2021 02:02 PM

Residents return home after claiming their cash assistance for those affected by the COVID-19 pandemic at the Brgy. Maricaban covered court in Pasay City on Aug. 11, 2021 as the capital region remains under enhanced community quarantine. Jonathan Cellona, ABS-CBN News
Residents return home after claiming their cash assistance for those affected by the COVID-19 pandemic at the Brgy. Maricaban covered court in Pasay City on Aug. 11, 2021 as the capital region remains under enhanced community quarantine. Jonathan Cellona, ABS-CBN News

China has administered 1.8 billion Covid-19 vaccine doses as of Wednesday, and is racing closer to herd immunity. But how will the country and others around the world deal with new variants that escape vaccine protection?

While experts said that vaccines are still effective against Covid-19, breakthrough infections and vaccine resistance linked to the Delta and Lambda variants are causing concern.

A British government advisory group has predicted a future in which Covid-19 will always be around, and recommends that authorities plan ahead for a more deadly variant or one that eludes vaccine protection.

The Scientific Advisory Group for Emergencies (Sage) predicted that future variants could be resistant to vaccines by using a different spike protein to bind to human cells. Many Covid-19 vaccines work by recognising the spike protein, according to a report by the group published on July 26.

The emergence of a variant with mortality rates similar to severe acute respiratory syndrome (Sars) at about 10 per cent or Middle East respiratory syndrome (Mers) at about 35 per cent was also a realistic possibility. Two different variants of Sars-CoV-2, the coronavirus causing Covid-19, could recombine and cause more infections and deaths, the report said.

Sage also proposed a scenario in which the virus’ virulence could decrease naturally as it adapts to the human host.

Sage has drawn criticism, including accusations of using dubious data and complaints that the British government has been too reliant on its advice. The British government was planning an inquiry into the handling of Covid-19 and Sage’s role in it, The Daily Telegraph reported in March.

Benjamin Cowling, an epidemiologist from the University of Hong Kong, said that the four scenarios in the report were worth considering. The most concerning possibility for him was a variant that could evade vaccines.

“I think the most concerning scenario is the second one, that a variant such as the Lambda variant will increase in prevalence and be able to escape current population immunity,” Cowling said.

“However, vaccinated people would probably retain protection against severe disease, so breakthrough infections would tend to be mild, and we might choose to manage Covid-19 like we manage seasonal flu,” Cowling said.

In the long term, it is quite likely that Covid-19 will escape current vaccine protections, but this also happens every year for seasonal flu, according to Cowling.

One way that the influenza virus changes is through “antigenic drift”, where small changes happen over time as the pathogen replicates, leading to the human immune system being unable to recognise it and trigger a response. This is almost certain to happen to Sars-CoV-2 as well, according to Sage.

Ashley St John, an immunology associate professor at Duke-NUS Medical School in Singapore, said concepts such as antigenic drift were first described for influenza, which is a very different virus.

“Antigenic drift happens much more quickly for influenza,” she said.

It may occur for Sars-CoV-2, given the large number of humans infected, but there is no indication that they would happen at the same rate as for influenza, according to the immunologist.

“Surveillance for variants, studying them and being prepared with vaccine strategies in the pipeline would all be important ways to invest in containing Covid-19,” St John said.

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