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By Luke Andrews for MailOnline
The announcement that Pfizer’s Covid-19 vaccine could be up to 90 percent effective has sparked claims that society could return to normal in the spring of next year.
But since most of the trial data has yet to be published, several scientists have given a cautionary note on whether the vaccine will work.
Does the vaccine really prevent infection?
Preliminary results from the trial say that of the 94 people who tested positive for the virus, no more than eight received the vaccine.
But little information has been published on how these infections were identified.
If the tests were only done after someone developed symptoms, asymptomatic infections may have been missed, meaning the vaccine does not prevent infection.
On the other hand, if all the trials, 43,500 volunteers, were repeatedly tested, this would reveal that the vaccine conferred immunity against the virus.
Furthermore, it is unclear what kinds of infections the eight who tested positive suffered, and thus whether the vaccine reduced some of the worst impacts.
Professor Eleanor Riley, an immunologist at the University of Edinburgh, said without further information it was unclear whether the vaccine reduced symptoms or stopped the infection.
How long will immunity last?
This remains tantalizingly confusing, and can only be revealed by continuing to monitor those who have received the jab.
Pfizer launched its trial in July and so far has not registered any candidates for whom immunity fell in the first few months, according to reports.
Several vaccines require reload injections every two years, due to decreased immunity. The diphtheria, polio, and tetanus vaccine, for example, must be given every ten years to ensure immunity.
Will the vaccine help the elderly?
Pfizer’s early launch has yet to reveal whether the vaccine will help the elderly.
Details about the ages of the 43,500 candidates in the initial trial are unknown, nor are the ages of those who tested positive for the virus.
However, if the virus was only tested in a middle-aged or young age group, this could mean that further testing will be required before it can be administered to older members of society.
Professor Tracy Hussell, an immunologist at the University of Manchester, previously warned that as people age, their immune systems become less sensitive, meaning a vaccine may not trigger the response required to provide immunity.
Who are the volunteers who tested positive for the virus?
Pfizer has not yet released information on the characteristics of the 94 people who tested positive for the virus and the at least eight people who contracted the infection despite receiving the vaccine.
This is important because it will reveal if the jab has managed to protect those most vulnerable to the virus or if they are still susceptible to it.
It will also reveal whether there is a significant difference between those who contracted the virus without receiving the vaccine and those who did.
