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Coronavirus: 10 questions and answers about the vaccine

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Three Coronavirus Vaccines before the Final Approval – What We Learned After Oxford University Announcement – What Phase 3 Means

The scientific community is on track to research into developing a vaccine that will shield humanity against the SARS-CoV-2 virus that causes COVID-19. However, a number of questions have arisen regarding the vaccine as a measure of protection against the new coronavirus. There are three vaccines that are already at an advanced stage of Phase 3 clinical trials, i.e. one step before submitting a request for approval to the relevant regulatory authorities.

These are the mRNA-1273 from the US biotechnology company Moderna, AZD1222, jointly developed by the University of Oxford in Britain with the pharmaceutical company AstraZeneca, and Ad5-nCoV, developed by Chinese biotechnology company CanSino Biologics. Based on the data that have come to light concerning Phase 1 of the clinical trial of the three vaccines, they appear to cause the development of a sufficient number of antibodies in the body of the volunteers vaccinated. This is a good basis for the continuation of Phase 3 clinical trials and a promising perspective on the usefulness of vaccines, whenever they are ultimately decided to be suitable for widespread use.

However, given the view that SARS-CoV-2 came to stay and therefore we must learn to live with it, as is the case with influenza and other respiratory viruses, we will attempt to answer 10 key questions concerning the COVID-19 vaccine. The answers are given on the basis of scientific data obtained to date from clinical research, as well as pre-existing knowledge from the development of vaccines Generally.

Which type of vaccine is most effective?

As mentioned above, three vaccines lead the scientific race for immunoprotection by SARS-CoV-2 out of 23 that are in the phase of the clinical trial on humans and more than 150 which are still in the research phase. Moderna’s is based on the so-called messenger RNA (mRNA), CanSino uses a non-copied virus vector and Oxford University’s a recombinant adenovirus-carrier. Each of these vaccine platforms has advantages and limitations. Important features include the speed and flexibility of construction, the safety and induction of a satisfactory immune response, the profile of the chemical and cellular immunogenicity, duration of immunity, scale and cost of manufacture, the stability of the vaccine. The most likely scenario is that no vaccine or vaccine platform will be able to meet all global needs on its own and therefore we will need more from one type of vaccine to meet the many different needs that may exist in different parts of the world and in different populations (e.g. younger people versus older people, special vulnerable groups, etc.).

How effective should the vaccine be?

A US study published in the American Journal of Preventive Medicine in June, based on a computational algorithm, concluded that the efficacy of vaccine should be at least 60% in order to be considered to be performing its purpose. Note that the seasonal influenza vaccine is effective ranging from 20% to 60% per year, while measles is 95%-98% respectively.

How safe vaccine will be?

Each medicine and vaccine, as found, is accompanied by side effects, the frequency and severity of which determine the safety of the final product. Preliminary clinical trials of the three vaccine candidates for COVID-19 have shown that the most commonly reported side effects were all mild to moderate in severity, fever, muscle aches, malaise, chills and a feeling of fever that can be treated with appropriate medicines.  In any case, due to the health situation caused by the pandemic, the Advisory Committees will weigh in detail the benefit-risk relationship before approval of any vaccine.

What percentage of the population needs to be vaccinated to stem the coronavirus?

Since any vaccine is effective and safe, another crucial factor that concerns scientists is how many people will need to be vaccinated against SARS-CoV-2 to shield humanity from a new pandemic. In the same US study, based on the algorithm, it is estimated that about 60% -70% of the world’s population should be vaccinated to stop the spread of SARS-CoV-2 in the community.

When will the vaccine be available?

The positive preliminary results of the clinical trials of the three vaccines have undoubtedly caused excitement in the public as well as in the scientific community. In fact, Dr Adrian Hill, director of the Jenner Institute at the  University of Oxford, has hastened to state that “a vaccine later this year is not considered unlikely. Of course, many things must be done correctly to achieve the goal within 2020”. However, independent experts estimate that before the middle of 2021 we should not expect the official release of a vaccine, despite the fact that some of the pharmaceutical companies involved have declared productive readiness. For example, AstraZeneca has announced that the first 15.2 million doses of AZD1222 will be produced by December 2020 and the remaining 15.2 million by January 2021. However, Mike Ryan, head of the Emergency Health Program at the World Health Organization (WHO), last week declared that “a vaccine against the new coronavirus cannot be expected before the beginning of 2021′, specifying that ‘realistically it will be the first part of next year before we start to see people to be vaccinated”.

When should the vaccination be given?

From experience with the seasonal flu vaccine to date, it takes an average of 14 days from the day of vaccination for a sufficient number of antibodies to be produced in the body and for the individual to be considered protected.

Therefore, a key question that also affects the effectiveness of the COVID-19 vaccine is when the vaccine should be given to prevent the body from producing antibodies. For example, preliminary data from AZD1222 show that it took 14 days for the body to produce T cells and 28 days for neutralizing antibodies to be detected. Theoretically, therefore, the vaccination should be done at least 1.5 months earlier than the beginning of the coronavirus circulation period.

Is a single vaccination enough?

Despite the encouraging results in developing a sufficient number of antibodies with the three vaccines mentioned above, the question remains whether the single vaccination will be sufficient to provide adequate protection. However, in Phase 1 of the clinical trials, all three scientific teams also gave a reminder dose to the volunteers. And this was done to test whether the booster dose helps to produce more antibodies, but also whether it helps to maintain the antibodies for a longer period of time. What is certain is that the vaccine, either in one dose, in two or more, should provide immunoprotection for more than six months to cover the release period of the new coronavirus.

Is the vaccine composition stable or modifiable?

From the scientific data so far, the new coronavirus has undergone some mutations since it crossed the borders of Asia and spread to Europe, America and the rest of the continents. The ability of viruses to mutate affects the effectiveness of vaccines. A typical example is the flu vaccine, which due to the predominance of different strains of the virus from year to year, its composition is parameterized to catch the predominant strains. Similarly, researchers are already studying this parameter in relation to SARS-CoV-2. Although it mutates slowly, surely any change in the virus can affect the action of the vaccine. At present, the mutations have helped it to spread more easily, but without this having affected the way the antibodies behave against the virus. Studies have shown that antibodies from patients with the original composition of SARS-CoV-2 offer protection against the newer version. This leads experts to believe that a vaccine with a stable composition will be effective against the new coronavirus.

A vaccine for everyone?

All vaccines under development for COVID-19 have one thing in common: their clinical trials are performed on healthy volunteers, aged 18-55 years. This practically means that vulnerable groups, such as the elderly, children and people with comorbidities and a burdensome medical history, have been excluded from research. The human immune system shows functional fluctuations with age and the general state of health of the individual. Simply put, the body of the elderly responds differently to a vaccine and otherwise to children. Therefore, before approving any SARS-CoV-2 vaccine, it should be clarified whether it is suitable for all population groups in order to be safe and effective. Of course, it is not excluded that it will initially be approved for healthy adults, whose vaccination will act as a protective shield for vulnerable groups of the population.

Vaccine affordable for everyone?

Regardless of when a vaccine for the new coronavirus will finally be approved for widespread use, several countries have already rushed to pre-order some doses of it. For example, Germany, France, Italy, and the Netherlands have pre-agreed with AstraZeneca to provide up to 400 million doses if AZD1222 proves effective, while Brazil and the United Kingdom have requested 100 million and the US 300 millions of doses. In fact, the US government has also stated that it will pay the amount of $ 1.95 billion to buy 100 million doses of the BNT162 vaccine, jointly developed by the American pharmaceutical company Pfizer Inc. and the German BioNTech if of course, it proves safe and effective.

From the above, it is clear that both the adequacy of the doses of vaccines produced and the price of the final product are small thorns in the fight against SARS-CoV-2. The WHO is in constant discussions with the manufacturing companies and its member countries to guarantee universal access to possible vaccines for all of humanity. “Vaccines for this pandemic are not for the rich, they are not for the poor, but for everyone,” Mike Ryan said emphatically. In the same vein, the drug companies Johnson & Johnson and AstraZeneca pledged at a related hearing in the US Congress to initially dispose of the vaccines without financial gain.

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