Our biggest hope to put an end to this deadly pandemic is to achieve herd immunity over time or to get a vaccine in the next few months. While we cannot be certain about the herd immunity scenario, getting an “effective” vaccine still looks propitious to save humanity from the clutches of the pandemic.
However, as we inch closer to the finish lines of the vaccine race, we should understand that it is impractical to hope that a vaccine with 100% efficacy will roll out in the market someday and suddenly the entire world will be free from COVID-19.
Even the “most promising” vaccine candidates cannot guarantee a very high effectiveness rate. In fact, the US FDA has set the effectiveness threshold at 50% to approve a COVID-19 vaccine. What this means is that the vaccine should be able to reduce the severity of the infection by at least 50%.
If you have been following the news, you would know that Oxford-AstraZeneca vaccine is one of the leading candidates in the race. However, in the first week of September, a case of adverse neurological illness in one of the subjects of the trial caused AstraZeneca to put a halt on the trials. As the trials were resumed shortly after, experts have raised critical questions pertaining to the safety of the vaccine. Notably, this was the second time that a neurological illness was detected in the participants of the Oxford-AstraZeneca vaccine trials.
Experts are concerned about AstraZeneca’s vaccine in light of these adverse cases and the possibility of new ones. People believe that certain events such as the US Presidential election is putting an immense amount of pressure on the development of a vaccine, even if it means compromising with the quality of the vaccine. Natalie Dean, biostatistician specializing in infectious disease epidemiology, stated:
AstraZeneca Releases COVID-19 Vaccine Trial Blueprint
AstraZeneca released a 111-page blueprint shortly after the claims questioning the safety and integrity of the vaccine surfaced the internet. In this blueprint, the pharmaceutical highlighted its goal of achieving 50% effectiveness to adhere to the guidelines issued by the FDA. In order to confirm this goal, there will have to be 150 people infected with the virus among those who received the vaccination or placebo shots.
However, according to the blueprint, an early analysis will be conducted when there are 75 cases and if the vaccine meets the target threshold at that point, the company will stop the trials and immediately push for regulatory approval to release the vaccine for emergency use.
AstraZeneca’s vaccine is based on a weakened version of the virus or adenovirus that causes infection in chimpanzees. Adenoviruses are attractive vaccine vectors to induce an immune response in mammals. However, the biggest drawback of this vaccine approach is the lack of adequate prior testing in humans. This approach has also caused some serious adverse effects in the past including the death of an 18-year old who received a gene therapy through adenovirus.
Keeping these factors in mind, experts have highlighted the problematic aspects of stopping the trial at an early stage. This includes the possibility of overlooking unusual side effects that might be prominent when millions of people get vaccinated. Moreover, a different troublesome aspect is that the effectiveness of the vaccine is mostly considered in mild cases of COVID-19, whereas ideally, the vaccine should target the moderate to severe cases to measure its overall efficacy.
According to multiple surveys, a lot of people are very circumspect about receiving vaccination due to the fear of improper testing. The two rare neurological cases in AtraZeneca’s trials have further pushed more uncertainty. Mark Slifka, a vaccine expert, Oregon Health and Science University, stated:
A report obtained by CNN showed that the affected volunteer, a 37-year old woman, experienced “confirmed transverse myelitis”. The woman could not walk properly and experienced weakness in her arms. Notably, the woman had no history of neurological illnesses of any kind. However, AstraZeneca stated that illnesses were “unlikely to be associated with the vaccine or there was insufficient evidence to say for certain that the illnesses were or were not related to the vaccine.”
Experts believe that the trials must not be rushed through especially since the details of the illnesses are not being revealed properly. In fact, AstraZeneca did not speak about the problem until the information was leaked by STAT News. Dr Peter Jay Hotez, a virologist stated, “the communication around it has been horrible and unacceptable.” National Institute of Neurological Disorders and Stroke stated that the lack of transparency from AstraZeneca can fuel mistrust in people and crush our hopes to get back to normal life with the help of a vaccine.
These are the reasons why experts are demanding a thorough investigation into the AstraZeneca vaccine to determine the safety and to instil confidence in people. Even in the US, the FDA has not permitted the trials to be resumed until it is clearly established whether the illness was caused due to the vaccine or if it was just coincidental.