Tuesday , December 1 2020

Reuters: First COVID-19 vaccine and herd immunity



On the other hand, major pharmaceutical companies are developing COVID-19 vaccines with good results. “Herd immunity” is a goal pursued by many countries, but experts say that the first vaccine will soon have a significant impact, Mediafax reports.

The last few weeks have brought good news, at least in terms of getting the most anticipated COVID-19 injections.

Pfizer is getting better. After announcing an efficiency rate of more than 90% for the new corona virus vaccine, the final analysis of the third phase study shows that the numbers are even better. The company says the vaccine is 95% effective in preventing infections, even in adults.

Moderna says the vaccine is 95% effective in preventing COVID-19, and expects similar results from Oxford / AstraZeneca in the near future.

Most likely, we will receive an approved vaccine in the coming months. But what causes the immediate spread of the SARS-CoV-2 virus? Although many hope to facilitate the so-called “collective immunity”, specialists are somewhat skeptical.

To develop a theory in this regard, Reuters reports that we must first find the answer to other questions: How fast does the virus that causes COVID-19 spread? Can the first vaccine stop the transmission of the virus? Or will they no longer make people sick? How many people agree to be vaccinated? Do vaccines provide the same protection for everyone? And the list goes on and on.

“Collective immunity is sometimes misinterpreted as personal protection,” says Joseph Jansa, a specialist in health prevention and the European Centers for Disease Control and Prevention (ECDC).

It is not appropriate to believe that I will be affected in any way because I have a collective immunity. “Collective immunity means the protection of the community, not the individual.”

The ECDC estimates that the injection limit is 67%. Meanwhile, 60-70% of the population that is immune to the new coronary virus is under discussion in Germany. Chancellor Angela Merkel said earlier this month that Germany’s anti-epidemic restrictions could be lifted.

WHO specialists cover 65% to 70% of the COVID-19 vaccine to reach herd immunity levels.

Eleanor Riley, a professor of immunology and infectious diseases at the University of Edinburgh, said: “Herd immunity aims to protect at-risk individuals. “The idea is this: for example, if 98% of the population had been vaccinated, there would have been so little virus in the community that the remaining 2% would have been protected. That is the goal.”

Calculations made by public health specialists are based on the reproductive rate or R value of the virus responsible for COVID-19. This value is a measure of the number of infected people by an infected person, usually transmitted by the patient under ‘normal’ conditions, without limit.

Under the hypothetical conditions of total vaccine efficacy, the finite percentage for herd immunity is calculated by dividing 1 by R, subtracting the result from 1 and multiplying by 100.

For example, immunity to highly contagious measles, if the estimated R value is 12 or higher, is only valid if at least 92% or more people are immunized. For viral virulence, which is responsible for seasonal flu, the value of R is around 1.3, the limit is only 23%.

“The problem is that we still do not know how fast the virus can spread without any precaution,” said Winfried Pickle, a professor of immunology at the Medical University of Vienna. The value of R “can be closer to 4 than 2”, he believes, despite the limitations, because the index is about 1.5.

Amesh Adalja, a scientist at the Johns Hopkins Center, estimates that the U.S. realism threshold will be 70%. However, the effectiveness of corona virus vaccines may increase that number depending on productivity.

Another important factor is whether vaccines administered by the authorities can stop the transmission of the virus.

Evidence to date shows that the first COVID-19 vaccine will at least stop the development of the disease in people who are already infected. However, there is a risk of contamination.

“While it’s great to protect against disease, it does not prevent the virus from circulating and getting vaccinated,” said Professor Penny Ward, a veterinarian at King’s College London.

Bodo Placher, deputy director of the German Institute of Virology at the University of Mainz, says it can be difficult to completely block respiratory infections with vaccines. But it is wrong to assume that the vaccine itself can stave off an epidemic.


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