Covid Vaccine Weekly: Both Vaccine Doses Needed For Good Protection Against B16172 Variant

31 May 2021

It’s been a concerning few weeks in the UK, with the B16172 variant first taking hold and then spreading to become dominant. This more infectious form of the virus, initially identified in India, is what we’re now going to have to live with – unless it is out-competed by another variant in the future.

Worryingly, experts had predicted that B16172 might be able to escape some of the effects of vaccines, which if true would threaten to derail the UK’s plans to finish lifting restrictions from the end of June. However, Public Health England (PHE) has looked at the ability of various variants to evade immunity, and says that the UK’s vaccines remain effective against the variants circulating, including B16172.

On the surface, this looks like good news. But delve a bit deeper, and things get more complicated, says Paul Hunter, professor of medicine at the University of East Anglia. PHE’s research found little drop-off in protection against B16172 among people who were fully vaccinated. But among those who have received just one dose, protection is considerably lower against B16172 compared to the previously dominant one, B117.

Plus, we can be pretty confident that B16172 is more infectious than earlier variants. This will magnify the effect of any drop in protection, meaning the UK could be about to witness a new spike in cases. Any prospect of a third wave arriving could have serious implications for the final stage of reopening in June.

However, there’s an important caveat here, argues Luke O’Neill, professor of biochemistry at Trinity College Dublin. PHE’s analyses are concerned with the risk of infection. But really, the most important question when considering the effects of variants breaking through vaccine protection is not whether someone gets infected, but whether they become severely ill or die.

So far, we don’t have an answer to whether B16172 causes more severe illness, or if vaccines still offer protection against severe illness if they fail to stop people developing COVID-19 symptoms. But, given the amounts of antibodies the vaccines typically get people to generate – as well as how effective they are at stimulating the immune system’s T cell response – it’s a reasonable prospect that they’ll remain highly effective at blocking the worst effects of COVID-19.

As Paul Hunter notes, we should have a better sense of how B16172 is affecting hospitalisation and death rates in the next few weeks. If these remain unaffected, then it’s far more likely that the UK’s exit from lockdown will be unaffected too.