Covid-19 Vaccine Update 3

On Monday, the world heard the claim from AstraZeneca-Oxford University that their Covid-19 vaccine showed an average efficacy of 70 percent, according to early results from their Phase 3 clinical trials. 

Questions are now being asked about the vaccine trials since it was revealed that a smaller set of participants (i.e. 2,741 volunteers) accidentally received a half dose followed by a full dose. 

It has also been revealed that only younger adults were involved, casting doubt on how effective it may be across the population. 

Nevertheless, this cluster appeared to show a 90 percent efficacy rate – as opposed to a 62 percent rate when two full doses were administered to 8,895 other participants. 

Prof David Salisbury (right), immunization expert and associate fellow of the global health program at the Chatham House think tank, said: "You've taken two studies for which different doses were used and come up with a composite that doesn't represent either of the doses. I think many people are having trouble with that″. 

Anyway, AstraZeneca’s chief executive Pascal Soriot (left) has admitted that they need to carry out “additional study” to validate the efficacy data. That is obviously, obvious! 

Still, the impatient UK government has resolutely moved to ask the Medicines and Healthcare products Regulatory Agency to assess the vaccine, bringing the country a step closer to a possible rollout. 

In the meantime, drugmaker Pfizer has provided an update around their Covid-19 vaccine Phase 3 clinical trial data, saying that the final result of their analysis of the 44,000-participant trial, had indicated a 95% efficacy rate. 

This is a better outcome than what Pfizer reported previously, when they announced a 90% effectiveness metric based on preliminary scrutiny of the Phase 3 trial data. 

This result also follows a preliminary data report from Moderna about their own Phase 3 trial of their vaccine candidate, which reportedly showed 94.5% effectiveness. 

Pfizer and partner BioNTech’s vaccine is an mRNA-based preventative treatment, similar to the Moderna vaccine. It does look like they should be roughly similar in efficacy – at least in the early offing, based on a limited sample of total cases and prior to peer review by the scientific community, which is yet to come. 

So far, the above tells us that this is all science by press release. 

There is a US FDA comment that I read which said that any coronavirus vaccine needs to be at least 50% effective to be useful in fighting the pandemic. Meaning, if you take the lowest figure of effectiveness for the AstraZeneca-Oxford jab, it still passes that benchmark. 

That may be so but it’s pertinent to note that real-world effectiveness is usually lower than the efficacy seen during trials.