The Ministry of Health has registered a nasal vaccine against coronavirus: what is known about it
The Ministry of Health has registered a nasal vaccine against coronavirus: what is known about it
On March 31, 2021, the Russian Ministry of Health registered the Gam-COVID-Vak (nasal drops) coronavirus vaccine, which must be sprayed into the nose using a special syringe nozzle.
It was developed at the National Research Center for Epidemiology and Microbiology. N. F. Gamalei. This is the world's first nasal adenovirus vaccine, which is very similar in composition to Sputnik V. However, there is much less data on the effectiveness of the nasal preparation than on the injectable Sputnik.
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This article is about the coronavirus disease, or COVID-19 . In all articles about coronavirus disease, we adhere to the position of the World Health Organization, or WHO. Before reading further, we recommend that you familiarize yourself with the WHO position on COVID-19 .
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How is a nasal vaccine different from an injectable vaccine?
The main task of vaccines is to train immune cells to recognize neutralized viruses or microbes, so that when they encounter live pathogens, the immune system is ready to repel the attack.
At the same time, immune cells are on duty not only inside the body, but also at the forefront, that is, in the mucous membranes of the nose, mouth and eyes. Border guard cells that have settled in the mucous membranes create protective antibody proteins that prevent pathogens from penetrating into the body. And the cells that are inside the body come into battle with pathogens only if viruses and microbes manage to break through the defenses of the mucous membranes and penetrate, for example, into the lungs.
Injectable vaccines only train immune cells that are inside the body. Over time, trained cells also enter the mucous membranes, but there are relatively few of them. As a result, even in vaccinated people, coronaviruses sometimes cross the mucosal barrier and meet resistance only when they are already in the lungs. And although vaccinated people get sick more easily than unvaccinated people, they can infect others.
Theoretically, nasal vaccines against coronavirus should train the immune cells of the mucous membranes to recognize the causative agent of the disease SARS-CoV-2. This could help to strengthen the very first line of antiviral defense, that is, to protect the vaccinated person from infection. Then he will not be able to transmit the infection to healthy people either. Thus, the creation of a nasal vaccine against coronavirus could be a major breakthrough in the fight against coronavirus disease.
What do we know about the Russian nasal vaccine
Vaccines against viral infections that can train immune cells in mucous membranes have been around for a long time. These are, for example, an oral vaccine against the polio virus, which works on the intestinal mucosa , and nasal vaccines against cold viruses, such as the flu.
However, all nasal preparations have so far been created only on the basis of live attenuated viruses. A new vaccine against coronavirus, created by the National Research Center for Epidemiology and Microbiology N. F. Gamalei, works differently.
Like the injectable Sputnik, the new drug contains a human adenovirus, from which the genes responsible for pathogenicity and reproduction were cut out, but the coronavirus gene was added. In the first and second doses of the vaccine, the adenoviruses are different, but the genes of the coronavirus are the same.
There is very little data on the effectiveness of nasal Gam-COVID-Vaka .Phase 2 clinical trials, which began in October 2021, should only end on December 31, 2023. The results of the study, which compared the effectiveness of nasal and injectable vaccines, have also not yet been published.
The results of animal trials of the vaccine are described in more detail, data on which were published in the instructions for the drug. Vaccine manufacturers write that the nasal "Gam-COVID-Vac" protects 100% of laboratory animals from a lethal infection. There is no information about how effectively this drug protects against infection.
There is even less information about the effectiveness of the vaccine in humans. The instructions only say that after the administration of the drug, the vaccinated volunteers developed antibodies to the coronavirus, both in the mucus from the nose and in the blood. And they have activated cellular immunity. We do not know exactly how many antibodies have appeared and how strong cellular immunity is compared to injection vaccination.
It is also impossible to compare the Russian nasal vaccine with foreign drugs. Although nasal adenovirus vaccines are being actively developed, say, in the UK and China , clinical trials of these drugs have not yet been completed. So we don't know how effective these drugs are at preventing infection , or if they work at all. There is nothing to compare the Russian vaccine with.
Who will be vaccinated with the nasal vaccine and how
The instructions for the drug say that the vaccine is intended to prevent infection with COVID-19 in people over 18 years of age. That is, the nasal vaccine is intended not only for the young, but also for the elderly. The medicine will be administered at the same frequency as the injectable vaccine: first, the first dose, and after 21 days, the second.
The contraindications for the nasal vaccine are almost the same as for the injectable:
- Severe allergic reactions in the past are anaphylaxis, in which the lips, face, tongue and throat swell, there is a sharp pain in the abdomen, and sometimes dizziness or fainting, nausea or vomiting, diarrhea. Common allergic reactions such as mild itching and nasal congestion are not a contraindication. If a person develops anaphylaxis after the first vaccination, a second vaccination should not be given.
- Infectious diseases and exacerbation of chronic diseases - in this case, vaccination is carried out 2-4 weeks after recovery. But if a person just caught a cold or caught a gastrointestinal infection, you can get vaccinated as soon as the temperature returns to normal.
- Allergic reactions to vaccine components. One of them, polysorbate 80, is also included in the nasal "Gam-COVID-Vac" .
It is not yet clear how safe the nasal vaccine is for people with autoimmune diseases and cancers - simply because there is no data on this. Therefore, people from these groups need to make a decision about vaccination together with their doctor.
Judging by the data from the instructions, when the nasal vaccine was used on pregnant animals, it did not harm either the mother or the fetus. However, clinical trials of the drug in pregnant women have not been conducted. Therefore, the creators of the drug recommend vaccinating pregnant women only from the 22nd week - at this time, the risks to the fetus are minimal.
Data on whether the vaccine can pass from the nose into the bloodstream, and from there into breast milk, is not yet available. Therefore, lactating women are advised to consult their doctor before vaccination.
How to get vaccinated - "classic" or nasal vaccine
As of April 4, 2022, 15,291 cases of coronavirus disease have been officially recorded in Russia . At the same time, more than one and a half thousand people were hospitalized, and 287 died. This means that the pandemic is far from over. That is, we must continue to protect ourselves from the coronavirus.
To reduce the risk of contracting the coronavirus, the Russian Ministry of Health recommends vaccinating six months after recovery or the last vaccination.
Theoretically, the nasal coronavirus vaccine has many advantages over the injection. It could help avoid infection, the injection, and associated local side effects such as pain and swelling.
True, it still would not protect against all side effects. The instructions say that adverse reactions from the nasal vaccine appear on the first or second day after vaccination and disappear on the third. Most often, the vaccinated have a fever, a headache, they feel weak and general malaise, and also complain of discomfort and slight swelling of the mucosa and throat.
In addition, very little is known about the nasal "Gam-COVID-Vak" so far. Until the results of clinical trials are published, vaccination with the Sputnik V injectable vaccine or revaccination with the Sputnik Light vaccine seems to be safer and more reliable ways to protect against coronavirus disease.
