For a moment, the corona virus did not completely dominate the news. The focus was on political The Hague, but the corona crisis is raging on. The hassle surrounding the vaccination campaign also attracted attention. There was also positive news from that front.
Among other things, the NOS spoke with Jaap van Dissel, director of the Center for Infectious Disease Control (CIB) of the RIVM, and Jacco Wallinga, chief modeler of the same RIVM.
This week there was good news about vaccinations from the US. The vaccines from Pfizer / BioNtech and Moderna not only protect well against getting covid-19, they also seem to significantly reduce the risk of transmission of the virus.
Van Dissel: “Well, there you say that research actually nothing left. The study is about the extent to which the vaccine protects against contracting covid-19. The participants are mainly healthcare personnel and emergency services, people at risk of increased exposure. In these interim results – because they are – you see that those people are very well protected after vaccination. But it has not been measured whether vaccination limits the transmission of the virus. “
Is the response to this study too positive?
Van Dissel: “It is a great study, with hopeful preliminary results. But the interpretation that also the NOS has given it, goes too far. The study proves that these vaccines are effective against disease. The question then is whether the conclusion you drew earlier, that vaccination prevents transmission, is justified on the basis of such an investigation. “
“Furthermore, it was examined whether vaccinated people with virus in the throat had complaints. This was almost always the case, except for more than 10 percent. Those results are in line with those of previous studies in Israel and the United Kingdom, for example. But that is not the case. the same as showing that vaccination actually reduces the transmission of the virus, that is, prevents you from infecting someone else. That was not the subject of study in the study. “
So what are the limitations of the study?
Van Dissel: “This is a cohort study in which care providers, firefighters, etc. were followed. To prove that vaccination also reduces transmission, you have to prove that a vaccinated person actually infects fewer people, in a natural setting where you also encounter unvaccinated people. that has not been investigated and certainly not demonstrated. “
Of the 3,950 participants in the CDC study, 72 percent were between the ages of 18 and 49 and 62 percent were women. Furthermore, 86 percent of the research group was white. Not a representative selection of the US population. Does that affect the eloquence?
Van Dissel: “It is a hopeful study because it shows that the virus occurs less often in vaccinees, but there are several explanations for this. For example, a cohort effect: in one setting everyone is vaccinated and so you cough each other less. You build your own. virus-free bubble. Furthermore, the research was also quite limited in the age categories. There were very few elderly people among them. “
“We know from a journal published two weeks ago in The Lancet Danish study that among those elderly, at least in Denmark, a second infection occurs quite often despite a previous first infection. In any case more often than in the younger groups. “
You do make a lot of comments.
Van Dissel: “Again, it is really a good study, but you must always keep a critical eye: what exactly does it say and what conclusions can we draw?”
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