Herd immunity would help us out of the crisis, Mark Rutte promised in March 2020. But despite a vaccination rate of 86 percent, we are in a ‘lockdown’ again. What about that group immunity? Immunologist Ger Rijkers explains.
1. Vaccinating would lead to herd immunity and save us from corona. Why do we notice so little of that?
“That is because we are now dealing with the delta variant of corona. The vaccines were tested during the alpha variant, which we then knew as the British. The delta variant did not yet exist and you could not get infected or transmit the virus if you received a shot. Now that the delta variant is dominant, the rules of the game have changed and many more people have to be vaccinated to achieve herd immunity.
Another factor to consider is how unvaccinated people are distributed. You can compare it as follows: suppose that the Netherlands is a large group of people and 90 percent has an umbrella. When it starts to rain, all those Dutch people put up their umbrellas.
The 10 percent who don’t have one can then hide under someone else’s umbrella. But suppose those 10 percent are all together, they still get wet. Now you see that there are places with more unvaccinated people and that is why a lot of infections take place there.”
2. How realistic is it that we will ever achieve herd immunity against corona?
“If a vaccinated person can still get infected with the virus and transmit it, we need more vaccinated to achieve herd immunity. Exactly how much is not certain, but what we have now is in any case not high enough because there are still many corona cases to be.
We’ll get the immunity eventually. Unvaccinated people come into contact with corona one way or another and if they get it and survive, they also have a good degree of immunity. Just like people who have been vaccinated. The more people get sick less, the less corona will spread. That’s how it eventually extinguishes.”
3. Was it known in advance that you could get sick despite the vaccination?
“We knew in advance that the vaccine would offer about 92 percent protection: that means that not everyone is protected against the alpha variant of the virus with the vaccine. Now that the delta variant is available, we are even less well protected. At Pfizer, that protection is only 50 to 60 percent, and with a Janssen jab even lower, about 30 percent.
Those mutations were in the back of the vaccine developers’ minds. Or in the forehead actually, because you always have to take into account that a virus changes, especially a new virus. For example, the flu virus is constantly changing, which is why vulnerable groups have to get a new flu vaccine every year. Fortunately, a coronavirus changes a little more gradually.”
4. A booster shot: is it okay afterwards?
“I think it will help enormously. When the current vaccines were developed, the subjects were followed for 3 months and it showed that the protection was very good.
At the moment we follow people longer and you see that the most vulnerable group is much less well protected 1 year after the vaccine. You saw that for the first time in Israel, because they started pricking there earlier. They have also had a booster shot there for some time and it appears that the contagiousness has gone down a lot.
The booster shot is still made based on the composition of the original virus that originated in Wuhan. So I would like to see the vaccine manufacturers make a corona vaccine 2.0 that fits better with the delta variant and therefore protects better. I assume that will happen now, but that is generally not discussed.”
5. What about the spread of the virus by vaccinees; to what extent do vaccines help against this?
“Looking at how well the vaccines help against spreading, it was still reasonably good at the beginning of the summer. The effect decreases a bit the longer you have been vaccinated, but the moment the delta variant emerged, the protection fell sharply. Especially in people who had received the Janssen vaccine, so the chance that they spread it also increases.
The fact that many people are now sick is due to various factors. It could be age, how long ago it has been since people got the vaccine, and now it’s winter too. Then it is much easier to transmit a virus than in the summer. In winter, the air is drier. A drop therefore evaporates faster and becomes smaller. If you inhale a large drop, it usually sticks to the top of your throat. A small one gets into your lungs faster and you infect each other faster.”
6. If herd immunity doesn’t work, how?
“If the past period has taught us anything, it is that the one and a half meters away helps very well. Face masks also protect 40 to 50 percent against contamination. But the best way to fight a virus is a complete lockdown: everyone has 2 weeks of but of course that is not possible, keeping the whole world indoors for 2 weeks.
There are now pills against corona. The tricky part is that you start the cure within 3 to 5 days after the infection: but you don’t always have complaints. If you do take them on time, the Pfizer pill will protect you 90 percent against hospitalization.
It can be a godsend for people for whom the vaccine does not work well. But there are not enough pills for everyone and they are not cheap. I recently calculated on a beer mat and then I came to 1,000 euros per person per cure.”