berkeman said:
Summary:: Have there been any studies trying to correlate the vaccine efficacy level with the severity of the side effects experienced with each vaccination?
(Sorry if this has already been addressed in one of the other COVID-19 threads. If it has, I can delete my question or merge it into the other thread. Thanks.)
I work part-time in EMS, so I was in tier 1A for public vaccinations for COVID-19 here in Northern California. I got my first Moderna shot a few days ago, and aside from some deltoid pain, I have not experienced any other side effects. I'm active on a Medic forum (EMTLife.com), and there is a long thread there for Medics to share their experiences with each of the doses of the vaccines (many of the full-time Medics are now past their 2nd dose). The side effects vary all over the map, seemingly independent of the person's background, medical history, and level of fitness.
So since I have experienced no side effects at all, I started wondering if that might be an indicator of how my body was responding to the first vaccination shot. Does it mean that my body is ignoring it, and I'll be in the 40% of folks who get no benifit from the first vaccine? Or is it a good indicator that my body handles infection challenges well (which is my history), and is building up the antibodies without bothering to tell me about it?
It would seem that the vaccine trials would have tracked side effects from each of the immunization shots, as well as antibody levels and whether the subjects were in the 90% that were eventually protected, or in the unlucky 10% who still lost the infection battle and developed full-blown COVID-19. Are any such study correlations published? I would be very interested to see what they have found. Thanks.
I think the measures of vaccine efficiency and effectiveness, are far more reassuring than you might think. First, the measures of efficiency are calculated during the initial trials when they look at the differences in disease incidence between the vaccinated and unvaccinated. These trials use specific population groups and try to use testing to confirm disease, this can mean the figures are less useful in predicting the effects in the general population.
The most useful measures are really the ones describing vaccine effectiveness, which are taken from large population studies. These by necessity are generally less objective and need large numbers, but they provide better real world data and often use different outcome measures, these can all give different numbers. The first consideration is the rate of infection seen in an unvaccinated population, or in the placebo arm of the study, so say you have a population of 100,000 people you might see around 1% becoming ill over a 3-month period, so around 1000 cases. You then compare this number to the disease incidence in the vaccinated group over the same period, if a vaccine offered 95% protection, you would expect to see 50 cases.
You might also look at different outcomes and estimate the protection against mild disease, serious disease, hospitalisation or death. When you look at the effectiveness in this way the protection offered against serious disease or death is usually very high, often close to 100%. Few fully vaccinated people develop “full-blown” COVID-19, the real surprising thing about these vaccines is in fact, how effective they are, developers were delighted with the results.
It's rarely the case that the COVID-19 vaccine has no effect, but there are lots of things that can affect the risk of developing the disease that are not dependent on the presence of antibodies. So it's a mistake to think 40% of people get no benefit, in fact the first vaccination is by far the most important, it's that the activates a wide range of immune responses, and this takes at least 3 weeks to get established, the second dose “boosts” these responses. So far there is no real evidence of one vaccine being better than others, there are to many other things to consider, a major one being the gap between the two doses, a longer gap might be better.
