Coronavirus: The Unanswered Questions About Vaccines

News broke last week that preliminary results from Pfizer and German BioNTech’s phase three trials of their corona vaccine show an effect of approximately 90 percent. The Oxford University vaccine candidate and AstraZeneca have also announced that they can give results in the last phase of testing before Christmas.

The European Infection Control Agency is now starting the approval process for a third corona vaccine.

Writes the European Medicines Agency EMA in a press release on Monday.

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According to the manufacturer Moderna Biotec, up to 94.5 percent is efficient.

At a time when much of Europe and the United States are hit hard by a second wave, news on vaccines is highly anticipated, something that could also be felt on the stock exchanges.

Researchers have never before been able to develop effective vaccines against other coronaviruses. Despite preliminary testing results, many unanswered questions remain about the most promising vaccines against the coronavirus that causes covid-19 disease today.

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Some go so far as to say that we cannot say if they reduce serious illness and mortality, or if they reduce the infectivity of the virus.

Mortality reduction

The well-known British Medical Journal (BMJ) is one of those who point to the latter, that is, very little is currently known about the effectiveness of candidate vaccines.

The reason is that the ongoing experimental phases are not designed to answer precisely this.

In all the ongoing trials of the leading vaccine candidates that have published the criteria for trials, there are very different groups that have been used as subjects. In the Pfizer and Modern trials, for example, people with a positive coronary test and mild cough are included in the study endpoint. The same applies to the AztraZeneca experiments, at least the one taking place in the United States, the magazine writes.

The reason for this is the relatively low number of all corona-infected people who become seriously ill and must be hospitalized. In these studies, which naturally involve a relatively limited number of people in the context of the corona, the probability of hospitalization is low.

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In final efficacy tests, tests are generally given after approximately 150-160 positive indications of the effect of the vaccine in terms of disease symptoms, regardless of severity.

Tal Zaks, Moderna’s medical director, explained to BMJ that the trials do not have a statistical basis to conclude that vaccines will reduce deaths caused by COVID-19.

– I would like to know what counteracts mortality? Absolutely, because I think so. I just don’t think it’s possible to conclude this within the timeframe of the study. Too many would die in the meantime, before we get the answer to that, Zaks has told the magazine.

Reduction of infectivity

The studies are also not designed to establish the importance of hospital admissions or whether it will stop human-to-human transmission of the virus, writes BMJ.

– Our study will not demonstrate prevention of infectivity. To do that, you have to test people twice a week for a very long period and it becomes operationally unsustainable, Zaks said.

Gunnveig Grødeland, Principal Investigator and Research Group Leader in the Department of Clinical Medicine at the University of Oslo, is an expert in immune systems, viruses and vaccine development.

She tells Dagbladet that she does not disagree with the conclusions drawn in the medical journal, but that she does not agree with the meaning of the conclusions.

– My first thought about this article is that it is about someone who is very in favor of so-called human provocation studies, in which you are exposed to the virus after receiving the vaccine. But then some completely different challenges arise, says Grødeland.

That infectivity cannot be concluded with certainty in the phase three studies that are now underway doesn’t really have much to say.

– First, the number of study participants had to be significantly reduced if infectivity measurement was to be tracked, and this would be at the expense of the opportunity to assess safety in a larger group of people. I think the security assessment is very important, so it is not a good idea. Second, as far as we know, asymptomatic people are less important for further spread of the virus, Grødeland tells Dagbladet.

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All of these phase three studies, now in the final sprint with a vaccine candidate, are based on tens of thousands of people who are naturally exposed. One of the advantages of these studies is that to a greater extent they take into account that people are different and therefore give a good picture of what will happen in a larger population after vaccination, Grødeland emphasizes.

Duration

Grødeland also emphasizes that it is common not to know more about factors such as the effect on hospital admissions at this point in the development of a vaccine.

In the case of a flu vaccine, one tries, among other things, to look at the statistics on hospital admissions in hindsight, but Grødeland says this varies somewhat from country to country.

Close gyms and pubs

Another thing we don’t know about is how long the vaccine provides protection for, Grødeland explains to Dagbladet.

– The data now shows that it takes about four weeks to build immunity. Pfizer data recovers one to two weeks after this again. What the preliminary results show here is that the vaccine works when antibody levels are at their peak. But it does not show how they are maintained or if the protection eventually wears off.

The vaccine expert believes that despite this, the vaccine can still be used to control the corona pandemic.

– With strategic vaccination, you will be able to stop the pandemic even if the vaccine is not effective for up to a year. Here it is important to be aware of what you want to achieve and when.

Effect on population groups

Pfizer’s preliminary results also say nothing about the effectiveness of this vaccine in different age groups.

Grødeland emphasizes that he knows that the elderly are included in the study, but assumes that they were probably included at a later stage of the study and that the effect will be less here.

– The effect of vaccines is usually less in the elderly population. More should have been known about what could be done to make vaccination more effective for the elderly. This is an important group to protect, especially in the context of covid-19.

Grødeland also emphasizes that researchers do not assume that a vaccine should provide 100 percent protection, but rather that it should provide better protection than it was initially.

– I think Pfizer’s results are very promising and better than I expected, says Grødeland.

– People are different, and vaccines do not always work for everyone. The reasons for this are something that is researched a lot, he concludes.