Corona vaccine: because it is not a guarantee of normality

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It seems almost within reach, the corona vaccine the world has been waiting for. Several vaccines are in crucial phase III, approval by the end of this year seems possible.

With him, therefore, hope and normality will also return. A normality without masks, without keeping your distance, without canceled birthday parties. When the vaccination is here, the danger of the new coronavirus is over, right?

Unfortunately, it is not that simple, write Malik Peiris and Gabriel M. Leung, doctors and professors of the University of Hong Kong in the journal “The Lancet”. Yes, according to experts, a first generation of corona vaccines is expected to be approved in late 2020 or early 2021.

But according to them, it will be more of another building block than the ultimate solution to stop the pandemic. They list three reasons for this – and thus show what we need to be prepared for in the long run.

1. A vaccine does not necessarily reduce transmission

Peiris and Leung assume a reproduction number of four. This number indicates how many people an infected person infects on average. If all protective measures are omitted, this number ranges from three to four for the new type of coronavirus, as experts from the first phase of the pandemic know.

If an infected person transmits the virus to an average of four people, then arithmetically about 25-50% of the population would have to be completely immune to SARS-CoV-2 following vaccination or disease to contain the further spread of the virus. , according to the researchers. . The problem with this is that the World Health Organization (WHO) recommends that vaccines reduce the risk of disease by at least 50%. The vaccines currently being tested are of this magnitude.

A vaccination doesn’t always stop you from getting the infection and getting sick, and therefore not passing the virus on to yourself. Scientists show what this means in practice with animal experiments. In primates, for example, vaccination usually leads to a reduction in symptoms and viral load in the lower airways. However, the viruses remain in the upper respiratory tract and become more widespread. So vaccination is not synonymous with immunity.

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2. Vaccinations probably don’t protect against new infections forever

While at least some people become immune to the virus as a result of vaccination, the important question so far is how long this immunity will last. Because with other pathogens from the cold-causing coronavirus family, protection often disappears after less than a year. Scientists have yet to investigate this in detail.

Experts also report that it is known from the related MERS-CoV virus that camels can reinfect themselves as natural hosts. However, it is not known whether they are as infectious as a first infection. “The observation that MERS-CoV occurs repeatedly in young and adult camels despite many initial diseases (> 90%), implies that transmission of the virus may not be functionally interrupted by a previous infection,” the experts said.

There are already some clinical cases for SARS-CoV-2, according to which people after surviving the disease were subsequently infected again, with a genetically modified variant of the virus. Therefore, it cannot be assumed that corona vaccines will greatly reduce or even completely prevent virus transmission and disease rate.

Scientists write: “The idea that Covid-19 vaccine-induced immunity allows the population to return to normal before Covid-19 may be based on illusory assumptions.”

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3. Different countries, different health systems

In addition to scientific concerns, the organizational distribution of corona vaccines will prove to be an additional challenge, Peiris and Leung continue. They refer to the different strategies of many countries.

There are some considerations as to which people prefer to receive the vaccine. The US National Academy of Medicine, for example, suggests this should be based on the risk of infection and the possible negative effects of sick leave on society. Politicians, doctors, nurses or even teachers would be among the first to receive a vaccination according to this consideration.

Others say people at high risk for severe relapse and mortality rates should receive the vaccine first. However, there is still a lack of data and empirical values ​​to establish whether this makes sense. Because some vaccines, such as flu vaccines, produce fewer neutralizing antibodies in older people than in young people, that is, they are more effective in young people. It will also depend on who gets the vaccine and when.

Depending on the country, strategies for purchasing and distributing vaccines may ultimately appear different, depending on the structural and economic conditions that need to be considered. Those who are not the first to be vaccinated will likely have to wait a long time before the vaccine is available for them too. And it will be less a matter of weeks than months.

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