Mosialos: what we know about the effectiveness of vaccines

The concerns that many people have expressed about non-mRNA vaccines of AstraZeneca, Novavax and Johnson & Johnson, in relation to vaccines mRNA of Pfizer/BioNTech and Moderna, are not justified by the data, particularly with regard to the likelihood of a severe and dangerous COVID-19. This follows from a lengthy Facebook post by the Health Policy professor Ilias Mosialos, of the London School of Economics and Political Science (LSE).

He points out that we were particularly fortunate because the first two vaccines to complete clinical trials (Pfizer/BioNTech and Moderna) were highly effective, with an efficacy of 95%, whereas the expectation of many experts was 50-70%. This was followed by announcements from AstraZeneca, Novavax and Johnson & Johnson and many people began to consider these to be ‘inferior’ vaccines. But are these vaccines really inferior or are they useful in the battle against the virus, Mosialos wonders, and his analysis suggests the latter.

The Pfizer and Moderna vaccines are 95% or 94% effective respectively in protecting against Covid-19 disease at all levels, i.e. mild, moderate and severe, as only 5% and 6% of those who get the vaccine will get sick.

The three vaccines from AstraZeneca, Johnson & Johnson and the Russian Sputnik-V are similar in development technology (viral vector), while Novavax's are protein-based. However, the results from their clinical studies report on different post-vaccination analysis periods, so neither these four vaccines can be compared one-to-one with each other, nor with the original two.

Oxford/AstraZeneca vaccine

In a recent pre-publication in «The Lancet» it was announced that the AstraZeneca vaccine is highly effective, 72% after the first dose. In fact 72% from day 22 to 90 days after the first dose and by 82% after the second dose, if this is done after 12 weeks.

The results of the Pfizer clinical study showed that on day 12 after the first dose the protection was 52% and increased to 95% by day 7 after the second dose. From the mass vaccination in Israel, these data are confirmed, as is the effectiveness of Pfizer's vaccine against the British mutation.

However AstraZeneca's (AZ) vaccine is 100% effective in preventing severe and critical symptoms from Covid-19 disease. As for 18% (100%-82%), on which the vaccine will not be effective, this means that with this vaccine, 18% of those vaccinated will become ill, but not with severe disease but with mild to moderate symptoms. None of those in 18% will become seriously ill, will not be hospitalized and, based on the data so far, no one who has been vaccinated will die if they catch the virus after vaccination.

AZ announced that the vaccine also covers the British variant.

Also, that the vaccine provides protection for severe cases and against the South African variant, but with the proviso that mainly young people were vaccinated and efficacy against this variant remains to be confirmed with results from a wider age range. Meanwhile, the company is modifying the existing vaccine to have a new vaccine covering the variants in October. This is being done to be 100% sure, as a booster dose may be needed and if needed, it will be best done with the new vaccine.

Mr Mosialos points out that the AZ vaccine will not be given to people over 55/65 years of age for the time being, because there was insufficient data for this age group, but this will be available soon. The decision of the European Medicines Agency (EMA) for the approval of the vaccine for the elderly, despite the small number of people tested in these age groups, was to make the options available in the Member States themselves ΕΕ.

He considers «based on the data we have, that there will ultimately be no age differentiation. But we will also wait for the collection of results from ongoing studies, so that we have a larger clinical sample to analyse. We need more data on the elderly when it comes to the AZ vaccine. Many countries, including our own, will not vaccinate people over 55 or 65 with this vaccine. As I explained above, this vaccine has also been proven safe and effective. But some countries have felt that the data for those over 55/65 years of age is not enough. We also know from the earlier phases of the clinical trial (with less data) that the over 65s who were vaccinated were effectively immuno-responsive after the vaccinations.

We also know that the -similar technology- Johnson & Johnson and Sputnik-V vaccines were also effective at these ages. So I don't expect there to be any age differentiation.».

Johnson & Johnson and Novavax vaccines

With regard to the Johnson & Johnson and Novavax vaccines, which were also reported to be less effective, their clinical trials, because they were conducted more slowly, also provided information on the South African variant, which had now emerged. We know from Johnson & Johnson's announcement that with a single dose there was 85% protection from severe infection for all ages (18 and over) for the first 28 days in all regions where clinical trials were conducted, including South Africa.

Also no serious infection or death from the virus was recorded 49 days after vaccination in all regions. In addition, protection was recorded on the 72% for those who glued the original strain and on the 57% for those who glued the South African variant.

Protection with the Novavax vaccine was recorded at 95.6% against the original strain, 85% against the British variant and 60% for those who got the South African variant. Again, these were mild symptoms of the disease and no deaths or hospitalizations were reported for those who contracted the disease after vaccination.

The transmissibility of vaccinated persons

Regarding the contagiousness after vaccination, Mr.Mosialos stresses that «we still don't have hard evidence that anyone who catches it doesn't transmit the virus. These data require thorough molecular analysis in vaccinees, usually on a weekly basis, and the question is being studied. We await data from vaccinations in Israel, which is ahead of the curve in both vaccinations and real-time analysis.».

So far, the data submitted by Moderna for the FDA review of the dossier showed that in the nasal swabs analysed (from participants and in the interval between the 2 doses) there was a reduction in asymptomatic infection of approximately 66%.

From University of Oxford we know - from a preliminary publication - that the percentage of positive molecular PCR test decreased by about half after two doses of the vaccine. The study did not measure transmission directly, for example by identifying contacts infected by vaccinees. But the researchers regularly collected nasal swabs from some of the participants and found that the PCR test positivity rate halved after two doses of the vaccine. This is considered important, because if the vaccine simply made the infections milder, there would not be a reduction in overall PCR test positivity (but a ‘quantitative’ difference in the PCR test result), as the authors argue.

Qualitative studies are needed to reduce transmission but also studies on longer periods after vaccination. We will have answers to these questions soon.

«It is important», says Mosialos, «that four companies (Pfizer, Moderna, Novavax and AZ) are already modifying vaccines to better protect us against the serious symptoms that (re)infections due to variants can cause. Scientists and companies are analysing the new data and modifying the vaccines accordingly. But it is important that governments and citizens respond with vigilance.

If the issue is not resolved globally, and the virus circulates unchecked in Latin America, Africa and Asia, particularly in immunosuppressed populations, we will leave room for the development of new strains or even -more unfavourable consequences- mutations. There is no time to lose - mass vaccination must go ahead globally.