Pfizer vs. Moderna and the truth about Sputnik V

The big current question, which prompted a meeting convened by the World Health Organization last week, is how to measure vaccine protection against Covid and its duration in time, after the application of the two doses. The answers are scarce, but some research is beginning to provide the first evidence.

The title of the conference, the content of which you have had access to Bugle, was: “Vaccines for Covid: will emerging data increase confidence in immune responses produced by vaccines for public health decision making and regulatory agencies? These decisions could include, but are not limited to, the need for the third doses.

The main objective of the meeting was to analyze the evidence on which the “best correlates of the protection afforded by the different vaccine formulas against Covid-19” are found. There were presentations from different vaccine development companies and Investigation groups, which put new information on the table.

The discussion was aimed, in part, at determining which specific components of the immune response (humoral or cellular) are more specifically linked to the protection provided by various vaccines. There was also a technical debate on the best statistical analysis and methodological designs clinical trials to be implemented to remove these doubts.

There is agreement on the great need for hard data to be able to evaluate “updated versions” “currently available prototype vaccines” – designed for the original Wuhan variant – compared to the Covid variants. The information available is scarce. This is why the WHO it particularly values ​​these jobs.

The meeting was chaired by Philip Krause, Deputy Director of the FDA. Coincidentally, on August 31, it was announced that Krause – a key official in the US approval of vaccines for children under 12 and the possible need for a third dose – will be leaving his post in November. Apparently, he viewed a statement by President Joe Biden about the vaccine recalls “as pressure” on the regulatory agency.

Also in attendance were Stanley Plotkin, creator of the rubella vaccine, and scientists from Oxford, Public Health England and the Icahn School of Medicine in Mount Sinai, New York. Also present were representatives of different pharmaceutical companies such as Janssen, Moderna, Medigen, Nanogenpharma and Geno-Inmune Medical Institute, among others.

First, data from a study recently published in the New England Journal of Medicine was presented. It shows that the efficacy of messenger RNA vaccines evaluated, in a study that included 19,000 health workers, fell to a 65 percent in July, while its efficiency had been 93% from May to June.

The authors, at the University of California, attribute the sharp drop in efficacy to Emergence of a delta variant and the end of mandatory chinstrap use and other restrictions in California, established June 15.

One of the most revealing information from this research was that the protection of Moderna’s messenger RNA vaccine it was still very strong, taking into account that the only health worker who had to be hospitalized was a not vaccinated.

A decrease was observed The most important in people who have received Pfizer compared to those vaccinated with Moderna. Pfizer showed an initial efficacy of 95 percent and Moderna, 94.1 percent. Say efficiency fell to 65 percent for Moderna et al 49 percent for Pfizer after 6 months.

On the other hand, a Mayo Clinic study showed that 6 months later After application, the efficacy of Moderna vaccine was 76 percent, while Pfizer’s was 42 percent.

The possible factors linked to this difference were analyzed, such as the intervals between the doses, which in the case of Moderna were longer (28 days for Moderna versus 21 days for Pfizer) and the different messenger RNA concentrations, Moderna’s vaccine is 100 micrograms and Pfizer’s vaccine is 30.

Then the results of two works on Sputnik were presented V. The first, published in the magazine Nature Communication, was led by Claudia Perandones, researcher at the Anlis Malbrán Institute, and Benhur Lee, professor of microbiology at the Icahn School of Medicine at Mount Sinai, New York. They evaluated the neutralization capacity of the variants, after providing 12 sera to health workers in Argentina.

The work evaluated the effectiveness of the vaccine against different strains and variants. It was concluded that it neutralizes the 100 per cent the Wuhan strain; the D614G mutation – present in Alpha (UK), Beta (South Africa) and Gamma (Manaus) – and the Alpha variant (UK). There is a slight reduction in the ability of Sputnik V to neutralize the E484K mutation -present in Gamma-, with a reduction of 2.8 times.

It was specified that the neutralization capacity of this mutation depends on the concentration of neutralizing antibodies, who stressed the importance of the second dose to ensure greater effectiveness. Subsequently, a moderate (6.8-fold) reduction in neutralization of the beta variant (South Africa) was observed.

The level of neutralizing antibodies is taken into account the best scorer vaccine protection, which was corroborated at the WHO meeting. To assess the efficacy against different variants, the researchers generated genetic engineering tools called “replicative competent vectors”, which allow “Clone variants” against which you want to assess protection.

Finally, the preliminary results of an article published as a “pre-print” in the magazine were presented. The Lancet (not yet rated by independent reviewers). It was directed by Rosana Nieves Chehín, from the Institute of Applied Molecular and Cellular Medicine, Tucumán, with the collaboration of Perandones and Lee.

Monitoring results 602 health workers, which received Sputnik V between December 2020 and July 2021, show that after 28 days antibodies developed in 97 percent of those vaccinated.

With statistical analysis, they concluded that after 90 days From the first dose, the titer of anti-RBD antibodies (specifically directed to the region of the spike protein that allows the virus to enter the cell) was still present in 94 percent of the volunteers tested.

However, as with other vaccines, at 180 days from the first dose (six months), these antibodies started to decrease. The rate of infections in the vaccinated with two doses of Sputnik V was 7 out of 602, 1.2%), comparable to a group of health workers from Israel, who received the Pfizer vaccine and were infected 39 out of 1497, 2.6%.

The study also showed that volunteers who had had a previous infection of Covid showed a rapid immune response, reflected in an increase in antibodies after the first dose of the vaccine. And another key fact: those people who have already been infected have shown between 5 and 20 times greater neutralization capacity against new variants of the Covid.

PS