Herd immunity: When will a vaccine against the new coronavirus appear? 

By | March 22, 2021

IN PERSONS WITH CORONAVIRUS INFECTION , antibodies remain in the blood for some time , which provide protection against re-infection – but only for a while. How long such immunity lasts is not yet known exactly, but presumably several months. The strategy of WHO and the ministries of health of different countries so far is to slow down the spread of infection by quarantine measures; for some time after this, herd immunity can protect the population, but then there will be a risk of another epidemic. A vaccine is needed to prevent it. It is now known about the development of at least 92 different vaccines (according to other sources , there are 79 of them), 22 of which are based on experimental technologies and contain DNA or RNA – and this can greatly speed up the process if everything goes well.

Why do we need vaccines

A vaccine is the only working way to “enhance” immunity, unlike dietary supplements or superfoods. Thanks to vaccination, it was possible to completely get rid of smallpox and greatly reduce mortality and the number of complications from many other diseases; The incidence of chickenpox, diphtheria and rubella decreased by 99 % by 2012 due to vaccination. There are infections that are ill 1-2 times, after which the immunity to them remains for life; that is why there was the concept of “measles” or “chicken pox parties” – children came to visit a sick person in order to get infected, to transfer the disease (usually in childhood these infections are easier than in adults) and to remain immune from it. It was a kind of vaccination – only much more dangerous than the introduction of a carefully designed vaccine, because the course of the disease was impossible to predict.

In today’s vaccines are very few contraindications (and some of their time), and the most frequent undesirable effects – pain, swelling or redness at the injection site. It is very important to vaccinate as many people as possible – then the so-called herd immunity is formed; once those who have received the vaccine do not become infected, the infection ceases to circulate in the population. And this means that those for whom the vaccine is contraindicated will not be infected – for example, people with severe immunodeficiencies who are undergoing chemotherapy, those who can not be temporarily vaccinated (for example, some vaccines are undesirable during pregnancy).

How they are developed

Typically, the development of a vaccine takes 10-15 years: first, there is the creation or selection of suitable molecules, then their preclinical studies in cell cultures and in animals. After that, if everything goes well, clinical trials begin: in order to register a product and bring it to the market, three phases of trials are needed . As with drugs, in the first phase, the vaccine is tested in several dozen healthy adults to make sure it is safe; at this stage the immune response can also be seen . In the second phase of the study more participants (up to several hundred), and some of them may be, for example, people from high-risk groups, in which the higher the probability of infection of the infections against which the vaccine is valid.

Phase 3 studies are large-scale, involving thousands or tens of thousands of people, to better determine how effective vaccines are in protecting against disease, and to discover even rare unwanted effects that may be associated with it. All these steps are preparation for vaccine registration. Registration is also a slow and difficult process , for which a detailed dossier must be prepared based on the results of all tests carried out. In Europe there is mutual recognition procedure – for example, if a drug or vaccine is registered in one EU country on the basis of the dossier submitted, other countries can recognize this registration, to withdraw the drug in the sale in its pharmacies.

In Russia, it is usually required that a drug undergo clinical trials with the participation of Russian patients; however, it is possible that due to the pandemic, registration in many countries will be accelerated – for example, the vaccine will be used immediately after its registration in the USA, China or one of the EU countries.

Traditional vaccines

Typically, vaccines contain either a weakened version of the bacteria or virus, or so-called antigens, such as virus surface proteins. Both options do not cause disease, but they provoke the production of antibodies that further protect against infection. The vaccine can also be a ready-made antibody – for example, this technology is used to protect against rotavirus infection. The search for coronavirus proteins that could be part of a vaccine began back in January.

Another direction is an attempt to protect the body from coronavirus infection with the help of existing vaccines, for example, against tuberculosis or polio. Some live vaccines stimulate not only specific (against a specific virus or bacteria), but also nonspecific immunity, that is, general innate defense mechanisms. It is possible that the anti-tuberculosis vaccine (BCG) can also protect against SARS-CoV-2. True, to find out, clinical trials are also needed – two of them have already begun .

What are gene vaccines

The problem with traditional vaccines is that they are not easy to produce: it takes a long time to perfect the technology and create such a production . If, instead of an antigen (viral protein), you use a gene sequence that encodes this protein, the process can be accelerated. With the introduction of DNA or RNA of a virus, the cells of the human body will themselves create a viral antigen, in response to which immunity will be formed. True, there is an important but: not a single DNA or RNA vaccine for use in humans has yet been registered. Nevertheless , the development of such vaccinations ( including against the hepatitis C virus, malaria and the Zika virus) has been going on for a couple of decades, so there is where to experiment with the genes of the new coronavirus.

Perhaps this particular pandemic will become the impetus for the emergence of new generations of vaccines against a wide variety of infections – if RNA or DNA vaccines really turn out to be effective and safe and begin to be widely used. Clinical trials of such vaccines are already beginning – for example, a study started in Seattle , which will include 45 healthy adult volunteers. In Germany, the experimental use of the RNA vaccine in humans has also begun – it is believed that this is the fourth vaccine in the world to enter the stage of clinical trials.

Injections, drops, plasters

The first association with vaccination for most of us is an injection; the advantages of this form are precisely metered dose, controlled (in the presence of a doctor) administration, well-established production. True, there are vaccines in the form of drops for oral administration (against rotavirus, cholera and polio pathogens ) or for introduction into the nose (against influenza). Work is also underway on fundamentally new methods of injection: these are patches with microneedles, tablets and sublingual gels, injectors for self-use. However, in these cases the cost and duration of production can become a problem .

During a pandemic, it can be difficult to provide the required number of injections with sufficient speed: they require at least minimally trained personnel to perform them . On the other hand, giving out to the public, for example, vaccines for oral administration without any control, is also risky: you can face mistakes when taking it or people forget about the vaccine, store it incorrectly, or simply throw it away for some reason. While most of the potential vaccines for SARS-CoV-2 are supposed to be administered in the most traditional way, in the form of an injection – and most likely, the first vaccine will be just that, because it is easier from a technological point of view.

When does the vaccine appear?

Vaccinations against the new coronavirus are being developed in twenty countries of the world, including Russia. If it usually takes about ten years and 500 million dollars to create a vaccine, from laboratory work to several phases of clinical trials , now we are talking about one and a half to three years and an increase in costs to three billion. However, the costs of pharmaceutical companies justify themselves: as soon as an effective and safe vaccine is ready, it’s hard to imagine a country that refuses its purchases.

Pharmaceutical giants, usually competing with each other, are joining forces – for example, the French Sanofi and the British GSK are jointly developing a vaccine against the new coronavirus, modifying an existing flu vaccine to contain the SARS-CoV-2 protein. It is assumed that the drug will be ready for clinical trials in the second half of 2020 .

For one vaccine being created in China, a second phase is already beginning to study – five hundred people will participate in it . If it is completed successfully, the third phase will begin, in which thousands of people will receive the drug. While experts agree in opinion that the vaccine will be widely available by the middle of 2021 year, and in a limited volume (for example, in the framework of the same third research phase) – early.

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