Implications of Being Vaccinated Against COVID-19

On Friday I received my first vaccination against COVID-19. It was the Oxford-AstraZeneca vaccine. I was aware of concerns about blood clots in some recipients of this vaccine, so why did I eagerly accept it?

Because data said accepting it made sense and rejecting it didn’t.

Oxford-AstraZeneca Vaccine and Blood Clots

The European Medicines Agency said there have been 30 “thromboembolic events” (embolisms, cases of blood clotting) in people who got this vaccine. That sounds like a lot, but out of how many vaccinations? About 5 million. (Many more have been done by now, but we’re only considering vaccinations done as of when the report was compiled.) So… the report indicates 3 in 500,000.

How often does embolism happen in everyday life? As it turns out, it happens on average to 1 person out of every 1,000 every year, fewer in younger people and more in older people.

On Friday, pundits weren’t yet saying on the news that most of the reported incidents may have been blood clots that would have happened anyway, part of the background rate of such episodes. But when I looked at the numbers, I decided that was likely, so I went for my jab with no worries about an embolism.

Sometimes being able to think your way through helps you understand and cope with hazards better, but in this case it helps dismiss warnings of a hazard that isn’t real.

Protection Gained

While I was looking into the vaccine in my body, I checked to find out how much protection I can expect from it. I got a few small surprises.

I was stunned (in a good way) to find that at least with this particular vaccine, the UK’s gamble of delivering the second dose after 12 weeks instead of the original shorter interval is paying off. At the original interval, two standard doses only produced an efficacy rate of 55.1 two weeks after the second dose. With the 12 week interval, efficacy is 81.3%. It isn’t as high as for the mRNA vaccines (Pfizer and Moderna) but the difference is not worth getting upset about. It’s high.

Right now I don’t have that much protection. It takes two or three weeks for the vaccine to take full effect. (I’m mentally counting down three weeks.) From then until my second jab kicks in, the efficacy rate is 76%.

What Does Vaccine Efficacy Mean?

To understand what this can allow me to safely do, I need to understand exactly what scientists mean by the term vaccine efficacy. Some vaccines protect against getting a disease. Not so, yet, against COVID-19.

Against COVID-19, the efficacy rate tells us how well a vaccine protects against getting sick enough to have symptoms. My chances of getting sick enough to know it will ultimately be about 1/5 what they were without vaccination, and if I do get symptoms I will not get as sick as I would have otherwise. I’m more likely to live and to avoid hospitalization.

My first dose of vaccine gives me no discernable protection against getting an asymptomatic case. A couple of journal articles claim data suggests the vaccine may reduce the viral load and thereby reduce transmission, but I can still catch the virus and spread it to other people without being aware that it’s happening.

Behavior Changes

How much can I ease up on behavioral restrictions?

If I care about people around me, I can’t ease up as much as some people want. Remember, my chances of getting sick enough to realize it will be greatly reduced, but not eliminated. I will still be able to get sick without being aware of it and will still be able to spread the virus. Some people aren’t able to get vaccinated no matter how much they want it. I don’t want to infect them.

Also, if we allow the virus to circulate freely among us, it will continue to mutate and eventually it will get past the vaccines. It could become more lethal in the process.

Even in late June when my second jab has taken full effect, it won’t be okay to stop using face masks and other precautions. I anticipate some outdoor gatherings during the summer with social distancing. I anticipate getting to see people a bit more and do a bit more, but I don’t anticipate going back to the way things were before SARS-CoV-2 emerged.

People who care about community, people who care about others and not only about themselves, will think the same way and will continue to practice some constraint. We have all learned in the past year or so which people around us are community oriented and which people are self-centered and selfish. In many ways that knowledge affects me more and causes me more internal upset than all the lockdowns and restrictions can… and it has shown me who I should most appreciate.

Primary reference: Single-dose Oxford–AstraZeneca COVID-19 vaccine followed by a 12-week booster. Ivan F N Hung and Gregory A Poland. The Lancet, 2021-03-06.