Fear of Death
The mortality rate for Covid-19 is quite low, but it is still a crap shoot. Certain factors make people more likely to die from the virus, but there is no guarantee that anyone who gets it will survive.
Given the pressure on hospitals of treating huge numbers of Covid patients, getting the vaccine, including the booster, which dramatically reduces the likelihood of hospital admission, and of death, is still a good idea.
Lots of people are expressing their fear of death as a result of the pandemic right now.