Two vaccines against the coronavirus passed phase II clinical trials

Two adenovirus vaccines were first and second phase of clinical trials in the UK and China. Most of the volunteers appeared as T-cell and antibody response (although the Chinese vaccine he was weaker); many have developed mild side effects. Scientists will continue to monitor the health and immunity of participants in research under the second phase, but the team from Oxford University is already beginning the third phase of testing. The results of the second research phase of the British and Chinese vaccine published in the journal The Lancet.

Of the 166 vaccines against coronavirus SARS-CoV-2, which are developing worldwide, 24 are under clinical trials (according to data from the who on 20 July). Among them, three adenovirus:n (she passes the second test phase), Chinese companies CanSino and Oxford University. The last two commands just told about the results of the second phase of clinical trials and proceed to phase three.

Vaccines nonreplicating viral vectors work as follows: in the genome of the attenuated adenovirus insert sections encoding proteins of SARS-CoV-2 (in vaccines from China and the UK used the S-protein shell of the virus). Adenovirus infects human cells, they begin to produce proteins of coronaviruses, the immune system recognizes and remembers them. As a result (in an ideal situation) produced the answer of two types: T-cells (directed against the infected cells) and the antibody (neutralizes viruses in the blood).

Researchers from Oxford under the leadership of Andrew Pollard (Andrew Pollard) tested his vaccine on 1077 healthy volunteers aged 18 to 55 years: half got the vaccine against coronavirus, and the control group from meningitis. 28 days after primary vaccination ten volunteers gave the second dose. 113 participants of the test also took paracetamol before vaccination and after a day or so researchers tested whether anti-inflammatory medication to reduce side effects. For health and immune response of volunteers at the time of publication of the results was observed for 56 days and will continue to follow the course of the year.

A vaccine for the coronavirus has caused more frequent and intense side effects (headache, weakness, fever, pain at the injection site) than the drug from meningitis, but did not lead to serious consequences — this level of safety is acceptable. The group, which took paracetamol, side effects are less frequent after the second dose of the vaccine have received it ten volunteers.

Vaccine called as T-cell and antibody response: the first peak occurred at 14 days after injection, the second at 28 days. The number of T cells recognizing S-protein of coronaviruses, gradually decreased after the peak and did not increase after the second dose of vaccine. But the number of IgG antibodies remained high during the 56 days of observation and increased several times after the second dose of vaccine. After 28 days of injection, 91 or 100 percent of the participants (results of tests) appeared neutralizing antibodies — they are not only recognized, but also successfully neutralized 80 or 50 percent of the live virus.

In China, a vaccine tests the group led by Wei Chen (Wei Chen) from Beijing Institute of biotechnology. The purpose of the test was to evaluate the safety and immunogenecity of the drug, but also to determine the dose for phase III clinical trials. So volunteers (all of them was 508, of these, 65 over 55 years of age) were divided into groups for each other have the principle about half of the participants received high dose of vaccine, and a quarter low (it matched the one that was used by the researchers from Oxford), and the remaining volunteers — a placebo. As participants were followed for 28 days, blood samples were taken immediately after vaccination and after 14 and 28 days.

More than 70 percent of the volunteers complained of side effects after vaccination. In most cases the reactions were mild or moderate, however, nine percent of participants who received a large dose of the drug had serious side effects, mainly fever. In the group with low dose and placebo serious side effects complained of only one and two percent of volunteers, respectively

T-cell immune response occurred in about 90 percent of volunteers in both experimental groups and was on average weaker than the British vaccine (11 sensitive to S-protein of cells per hundred thousand mononuclear cells vs. 856 per million). Neutralizing antibodies appeared in 59 and 47 percent of the participants who received the large and small dose, respectively.

The authors note that the study has an important limitation: volunteers were recruited from the Chinese Wuhan, and at the beginning of the study, many participants already had basic immunity to SARS-CoV-2. According to estimates of researchers, the level of basic immunity of volunteers corresponds to the average for China, but in other countries the figure may differ — it is necessary to consider the conclusions of the test results.

Researchers from both groups remind you that before the end of clinical trials far, you should test the vaccine on a larger sample, which will include people of different nationalities and races, the elderly, and people with underlying medical conditions. The team from Oxford University has already started this task, and recruiting volunteers for phase III trials in the UK, Brazil and South Africa.

The other day there was a message that the company “R-Pharm” agreed about the production of the Oxford vaccine in our country. Details about the developed in our country vaccine against coronavirus, their types, advantages and limitations we described in the material “On the tip of the needle”.

Alice Bahareva

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