Company Pfizer posted on the website medrxiv.org Preprint with the results of the first clinical trials of its vaccine against the new coronavirus. In response to two doses in patients proportional to the dose of vaccine increased the levels of antibodies to SARS-CoV-2 appeared temporary ailments, like weakness or pain in the injection site. Tolerability and sufficient immune response, the number of antibodies was comparable to that we recover, — suggests that the vaccine works as intended by the authors and they plan to continue the clinical trial.
Now around the world is developed more than a hundred vaccines from the new coronavirus. Among them there are different options, among which quite a lot of vaccines based on nucleic acids. None of the vaccines of this sort have not yet registered, but many of them have already passed safety tests and are considered quite promising. mRNA enters the cell and based on it, synthesize parts of the virus as if it actually infected her. This in theory should provoke the correct antiviral immune response. This vaccine is quite safe, — its molecules are unable to integrate into the genome and utilized by the body as normal mRNA.
Another practical advantage is especially important when the required vaccine is needed quickly and in large quantities — low cost of production and the speed of development: you can take over the proven and developed once mRNA-design and change only a small area to get the vaccine to completely different diseases.
Despite all the potential advantages of RNA-vaccines, they have a significant drawback — provoked immune response is often weaker than desired. To solve this problem, scientists optimize methods of delivery of RNA into cells and use a multiple vaccination.
It is on this class of vaccines in the race coronavirus medications were supplied by Pfizer. BNT162b1 is a molecule of RNA coding for the antigen as the receptor-binding domain of the S protein of SARS-CoV-2 is the major target for neutralizing antibodies. Experts Pfizer modified RNA, replacing part of originof 1-methyl-pseudouridine — it helps to increase the amount of protein obtained from one molecule and enhances immune response. B-cells of the immune system of our “like” polyvalent antigens, which have different areas for recognition, and to ensure this, the scientists added a molecule of RNA a piece of the gene that encodes trimerization domain phage protein (a common practice). To increase the chances of the vaccine to get into the cells, the molecules are Packed in the lipid nanoparticles.
The first phase of clinical trials BNT162b1 conducted on 45 adults aged 18-55 years. This double blind randomized study in which 36 patients were injected with 10 (n=12, twice in 21 days), 30 (same), and 100 (n=12, single) milligrams of the vaccine, and the remaining 9 received a placebo. After vaccination, participants checked the level of neutralizing antibodies in the blood and followed the side effects on the basis of questionnaires.
The main complaints of patients during the week after vaccination were associated with pain at the injection site, weakness and headache, and the majority described these symptoms as mild or moderate. Individuals who received large doses, reported severe pain (1), fever (1) and insomnia (1) within one of the first days after vaccination. The group who took a placebo, side effects were expressed significantly weaker.