A single Covid-19 vaccine could be effective against all current strains

1 Sep 2020

Microscopic close-up of the Covid-19 virus. Image: © sdecoret/Stock.adobe.com

An analysis of more than 18,000 SARS-CoV-2 genomes suggests that mutations in Covid-19 are rare.

While countries around the world continue to monitor the number of daily infections, scientists are working hard to learn as much as possible about Covid-19 in order to develop a safe, effective vaccine.

Now, in a study published to the Proceedings of the National Academy of Sciences of the United States of America, research suggests there is limited diversity of the novel coronavirus, SARS-CoV-2, meaning a single Covid-19 vaccine could be effective against all known strains.

Researchers studied more than 18,000 SARS-CoV-2 genomes sampled since December 2019, performing phylogenetic, population genetics and structural bioinformatics analyses.

An early discovery in Covid-19 research found that a viral ‘spike’ protein binds to a receptor on human cells known as angiotensin-converting enzyme 2 (ACE2). As such, many vaccine candidates focus on the spike protein, as it plays a key role in viral entry and can be targeted with neutralising antibodies.

This latest research suggests that mutations in the SARS-CoV-2 genome are rare, particularly in the spike protein, and that even the few mutations that have become widespread likely did so by chance. This means a single vaccine could be effective against all currently circulating viral strains.

‘Cautiously optimistic’

Viral diversity has challenged vaccine development for other viruses such as HIV-1 and influenza, but this latest research suggests that these viruses each constitute a more diverse population than SARS-CoV-2 viruses.

While it’s still extremely early in terms of research into Covid-19, the researchers said that the SARS-CoV-2 viruses that are currently circulating constitute a homogenous viral population. The findings suggest that “drift and bottleneck events” can explain the minimal diversity found among the virus genomes rather than adaptive selection.

“We can therefore be cautiously optimistic that viral diversity should not be an obstacle for the development of a broadly protective SARS-CoV-2 vaccine, and that vaccines in current development should elicit responses that are reactive against currently circulating variants of SARS-CoV-2,” the researchers wrote.

FDA chief may fast-track Covid-19 vaccine

This research comes at a time when the head of the US Food and Drug Administration (FDA) Stephen Hahn said he is considering fast-tracking a Covid-19 vaccine by bypassing the normal approval process.

According to The Irish Times, Hahn said the FDA was prepared to authorise a vaccine before phase three clinical trials were complete, provided the benefits outweighed the risks.

Hahn said that the fast-tracking of a vaccine could be done safely through an emergency authorisation, meaning it would only be given to certain groups. “Our emergency-use authorisation is not the same as a full approval,” he said.

However, bypassing the normal approval process for vaccines has been criticised by several official health bodies, including the World Health Organization (WHO).

Last month, Russia approved an experimental Covid-19 vaccine before testing had been complete, with the country’s president Vladimir Putin claiming the vaccine was safe for human use.

In urging Russia to comply with all stages of testing, WHO spokesperson Christian Lindmeier said: “Sometimes individual researchers claim they have found something, which is of course, as such, great news.

“But between finding or having a clue of maybe having a vaccine that works, and having gone through all the stages, is a big difference.”

It has now been six months since the first case of Covid-19 was identified in Ireland, and while researchers continue to learn about Covid-19 and scientists all over the world race to develop a vaccine, global cases of the virus have now passed 25m.

Chart shows global confirmed Covid-19 cases. Image: Statista

Jenny Darmody is the editor of Silicon Republic