Is it right not to test the updated vaccines for Covid on humans, as happens for the flu?

When will updated Covid vaccines be approved in Europe?

The European Medicines Agency (EMA) has scheduled an extraordinary meeting for Thursday 1 September for the approval of the first Covid vaccines updated to Omicron presented by Pfizer and Moderna. Pfizer presented a trivalent vaccine with Wuhan, BA.4 and BA.5, dominant in Europe and the United States, but with final testing only in mice (clinical data, as for Moderna, are available on Omicron 1). The company confirmed in a statement that human studies have yet to begin. Moderna has proposed an updated vaccine on the original Wuhan strain and BA.1 (now disappeared), already approved by the UK, but is working on an update on BA.4 and BA.5 which should be ready within a month.

What happens in the United States?

The U.S. Food and Drug Administration (FDA) is expected to approve the new updated Pfizer vaccine against Omicron 4 and Omicron 5 variants this week. The United States aims to start a new vaccination campaign immediately after Labor Day (September 5) but no new clinical data will be available by that date: the pharmaceutical company has stated that a clinical study investigating safety, tolerability and immunogenicity of the vaccine is expected to begin in September, which means that the FDA will not have this data available. However, a commission of experts consulted last June by the FDA established that the new vaccine is very similar to the original one, there is a lot of information on the production platform of mRNA products and therefore it is possible to approve the boosters before clinical data are available. The new booster will in fact be identical to the original vaccines, except that it will contain the genetic code for two versions of the protein used by the virus to infect cells: the protein from the original vaccine and the proteins from the Omicron BA.4 and BA subvariants. 5.

Why does the FDA want to speed things up?

The goal of having a vaccine not against the current virus, but against what is to come was said during the meeting last June of the FDA’s panel of independent experts that suggested that the Agency approve the BA.4 vaccines. BA.5 without clinical data. Even with rapid technologies such as messenger mRNA used by Pfizer-BioNTech and Moderna, it can take three months from the creation of a new vaccine to its mass production. It would take at least four more months to obtain updated clinical data. It is not possible to do an efficacy study on every variant – he reflects Sergio Abrignaniprofessor of Immunology at the University of Milan – and at the same time to keep production going, there is no time because the virus runs faster and we would end up with a vaccine that is out of phase with the one that circulates.

right not to test updated vaccines?

The decision is based on the high confidence of vaccine platforms, which have already proven effective against previous strains. It is also unlikely that smaller vaccine studies will provide much information on the known side effects of vaccines. Events such as myocarditis, inflammation of the heart, which occurred mainly in young adult men, are so rare that they were not detected even in large-scale clinical trials, but only after the start of mass vaccination. If the same technology is used, already validated for safety (the vaccine has been administered to over one and a half billion people) and only the sequence or number of amino acids and nucleotides is changed, it can be assumed that the vaccine induces an immune response comparable to the one induced by vaccines in which efficacy was measured confirms Sergio Abrignani. From what we know after two years of experience there was no fatal adverse event directly associated with the vaccines and the rare post-vaccine myocarditis resolved rapidly with a few days of therapy. The post-marketing observation remains fundamental that the one that made us discover myocarditis and, for viral vector vaccines, the other rare adverse effect of thrombosis (one death in a million vaccinated).

Are we moving towards a path already used with anti-influenza vaccines?

The influenza vaccine is updated every year based on the recommendations of the World Health Organization regarding the most circulating strains. Updating influenza vaccines does not require the submission of new efficacy data, which is only assessed at the end of the season and typically never exceeds 50-60%. Until two or three years ago – adds Abrignani – small clinical studies on the new flu vaccine were required in the order of a hundred people. Now, however, only “regulatory aspects of production consistency” are evaluated, that is, parameters are controlled that must be consistent throughout the production line: there must be a certain amount of protein (in the case of influenza) and its characteristics must indicate that healthy, intact and immunogenic: they are all chemical-physical laboratory assessments and no human trials are performed.

Do they all agree on the idea of ​​not continuing with clinical trials?

In the United States, the debate is heated: some scientists argue it would be better to wait for human tests because not enough is yet known about Covid mRNA vaccines to handle them like anti-influenza (but the risk would be to postpone vaccinations with updated products to BA.5 late winter) other scientists are of the opinion that the vaccine structure is more or less the same, that clinical data exists on Omicron 1, that billions of people have already been vaccinated and therefore laboratory tests on guinea pigs, as is already done with anti-flu. In the US, about 450,000 people die from Covid every day and the number could further increase as people stay indoors longer, so there is a rush to have an updated vaccine in particular to protect the most fragile. Doctor
Anthony Fauci
he explained that using animal data is nothing more than what we do every year in updating the flu vaccine. John Moorean immunologist at Weill Cornell Medicine, recently stated that the data on mice cannot predict what will happen to humans and that government plans could backfire against whether autumn or winter brought a wave of disease despite the updated boosters, thus reducing the general confidence of Covid vaccines.

Will people make the new vaccine?

Aside from the clinical efficacy debate, the debate could impact an even broader question: Will people get a new Covid vaccine booster? The new boosters will push Americans to make the new vaccine because it is more effective? Or does the fact that there have not yet been any human studies with Omicro 4 and 5 make them more reticent?