Vaccine shot (illustrative)
Vaccine shot (illustrative) Flash90

Reports this week that a vaccine for Covid-19 being developed by German pharmaceutical company Pfizer is 90% effective have given rise to relief and rejoicing across the world, with world leaders responding that “the end is now in sight.”

Nonetheless, speaking at a webinar to the Board of Trustees of the University of Haifa this week, Professor Richard Horton, editor of the Lancet medical journal said that “there are question marks surrounding the vaccine.”

He highlighted “the impact on different groups in the population” adding, “and more” before concluding that “we have reason to be optimistic.”

In July, Horton granted a lengthy interview to the Washington Post in which he emphasized that “a vaccine is not going to take this virus out of our society. A vaccine is never 100 percent effective, 100 percent safe, and available to 100 percent of people … I’m pretty sure we’re going to have a vaccine next year, but that isn’t going to mean we’re going to be able to go back to our fully normal lives.”

All the same, 90% efficacy is pretty impressive. By way of comparison, the flu vaccine’s efficacy is estimated at anywhere in the range of 30% to 60%, and has to be administered at least once a year. But what does that 90% actually mean?

Pfizer enrolled 43,538 people in its study, in the so-called Phase 3 stage of its trials. Each volunteer was given either two doses of the vaccine or two salt-water placebo injections. 94 people reportedly contracted Covid-19 during the trial. Based on the data – which was not released along with the announcement – Pfizer declared that the vaccine had been shown to be 90% effective.

However, according to reports, the trial only considered people to have “contracted coronavirus” if they showed symptoms and also tested positive. Trial volunteers (both in Pfizer’s trial and those conducted by other pharmaceutical companies and research teams) were and are not regularly tested for coronavirus if they fail to exhibit symptoms.

Critics of the vaccine trial say that given what we know about coronavirus by now i.e. the high percentage of carriers who are asymptomatic, this appears to be an astonishing omission. In the theoretical case where 100% of the population agrees to be vaccinated, this caveat is less significant, as 90% of people will likely be prevented from developing serious illness as a result, if the data is proven correct. However, they say, given that this is unlikely to happen, the omission is certainly worrying.

The trial does indicate that those vaccinated may be unlikely to die from coronavirus, but since only those with symptoms were tested for coronavirus, those who still contract it but remain asymptomatic are still perfectly capable of passing it on to unvaccinated individuals who may suffer serious consequences. In a nutshell, critics say that a vaccine that fails to prevent asymptomatic cases as well as more serious ones is simply not going to stop the pandemic.

Pfizer has predicted that it could have over one billion vaccine doses ready by next year, but given that there are around 7 billion people in the world, that’s clearly not enough. They add that given that governments are already racing to be first in line to receive those shots, it also seems unlikely that a global program to ensure that the available vaccines reach those most vulnerable stands any chance of being implemented, let alone planned and designed.

Unless a country buys enough doses for its entire population, they explain, and forces everyone to be vaccinated, a future of border controls, “red” countries, and ongoing outbreaks seems the more likely prospect than “defeating this virus.”

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