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‘We cannot abandon coronavirus measures until vaccines are shown to prevent virus transmission too’

All acute care staff at Leiden University Medical Center have received their first and sometimes even their second dose of the coronavirus vaccine. But how long will you be protected after vaccination and what does the genetic material of the virus do in the vaccine? Our virologists Ann Vossen and Leo Visser answer these and other frequently asked questions.

Ann Vossen, virologist in the Department of Medical Microbiology, and Leo Visser, head of the Department of Infectious Diseases, are both very optimistic about the vaccines that have been approved. ‘The mRNA vaccine from Pfizer/BioNTech that was administered in the LUMC does a remarkably good job of preventing people from contracting the coronavirus. The studies are still ongoing, but the effect appears to be much better than expected, with an effectiveness of up to 95%. That means that out of 100 people who get this vaccine, 95 will be protected against coronavirus.’

In addition, it produces a good immune response in elderly people. ‘That's actually quite unusual, because normally a vaccine is less effective in older people,’ says Vossen. Studies on this vaccine show that the Pfizer vaccine works as well in the 65+ group as in the group of under-65s. ‘That's obviously very good news because that is also the group we primarily want to protect.’

Genetic material in a vaccine

Both Vossen and Visser are also enthusiastic about the new vaccine technology used by Pfizer/BioNTech and Moderna. Indeed, this is the first time that mRNA technology has been used in a registered vaccine for humans. ‘mRNA vaccines are designed for rapid production in situations that call for it, such as the current pandemic,’ says Vossen. These vaccines do not use the familiar attenuated virus particles or virus proteins, but a piece of genetic material from the virus. ‘This mRNA is made in such a way that it can enter our cells. There, the genetic material is translated into a virus protein, the spike protein in this case. The cells present these spike proteins to your own immune cells. They, in turn, produce a powerful immune response to the spike proteins,’ Vossen explains. The difference compared to an attenuated virus vaccine is that with an mRNA vaccine, your body first has to convert the genetic material from the vaccine into a protein itself.

A flexible vaccine

That also has an advantage, says Vossen. ‘That’s because of the way it’s produced. If we discover a strain against which this vaccine does not work, it is relatively easy to modify the vaccine. Only the genetic code would need to be changed, not an entire protein. So, a vaccine like this simply provides more flexibility.’

Coronavirus rules continue to apply

The vaccine that our acute care staff have received works very well in preventing someone from falling ill with coronavirus. But does that mean they no longer have to follow the coronavirus rules? ‘No,’ Visser says, ‘we still don’t know whether you can still be contagious after vaccination. You can assume that if you cough and wheeze less, you will pass on the disease less easily, but it is not yet known whether vaccination prevents infection entirely. As long as there is uncertainty about this, you will unfortunately still have to adhere to the coronavirus measures in 2021.’

Relieving the strain on health care

Visser has already received his first vaccination. ‘Because of my age, I belong to the risk group,’ he explains. ‘Older people have a greater chance of becoming seriously ill from the coronavirus. In the early stages of infection, their immune system is less able to prevent the virus from multiplying.’ But he also has another reason: ‘I want to help relieve the strain on the health care system. By doing so, I make a positive contribution to society.’

Vossen will have to wait a little longer for her vaccination, but she is already looking forward to it. ‘I think we have to do everything we can to prevent ourselves – as well as the people around us, like family and friends – from getting ill with the coronavirus. I also am happy to be able to do my part to slow down the spread of the virus.’

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