Can you get a vaccine after receiving a placebo?

What is in the placebo? Is the recipient of a placebo aware of it? Can a person who has volunteered for the placebo get the Covid vaccine? These are some important questions which are on everyone’s minds as people in certain corners of the world start to receive the Covid vaccine and others hope to do so soon.But now people are in fear to volunteer for a vaccine trials because of hidden doubts in their minds. Dr.Satyajit Rath , Immunologist , IISER,Pune responds to all these anwers.

1. How a volunteer would know whether he has taken a placebo or a vaccine for COVID-19?

No, they will not know. In fact, not even the people giving the injection will know, in all likelihood. That is why these are called ‘blinded’ trials; the people taking the experimental vaccine (or ‘candidate vaccine’) and the people monitoring it will not know who has got the ‘vaccine’ and who has got the ‘dummy vaccine’ or ‘placebo’ (so they are ‘bind’ to that information!). That way, that knowledge will not affect what they do and how they behave, which will reduce the possibility of bias in the study.

2. What is the difference between placebo and Vaccine?

A ‘placebo’ is a ‘dummy vaccine’, in the sense that it looks like the ‘vaccine’, but does not have any of the active ingredients of the ‘vaccine’. So the ‘placebo’ would have no real effect at all. Placebos are used so as to have a group to compare the ‘vaccinated’ group with, in order to see if the vaccine ‘works’. It is, effectively, an ‘unvaccinated’ group, except that group is getting a ‘pretend vaccine’ so as to maintain ‘blinding’ in the trial.

3. Do you think if a person takes a placebo then he/she can’t take a vaccine? if no then why?

No no; of course, people taking placebos in a vaccine trial can, should and will get the actual vaccine if and when the trial is successful and the vaccine is seen to work!

4. What test can be done to know about the safety and effectiveness of a vaccine?

The safety and effectiveness of an experimental vaccine cannot be tested by anyone ‘test’. It is a structured process of first ‘pre-clinical’ testing in experimental animals in which safety and the ability to generate a useful immune response are tested, and then the three phases of trials in humans, in which safety is tested (phase 1), the ability to generate an immune response is tested (phase 2), and then the actual ability to protect against the disease is tested (phase 3). All of these have been and are being done for all COVID-19 vaccine candidates.