About two weeks after you are vaccinated, your anti-corona antibody level is at its highest and you are considered fully vaccinated.
However, as some people discovered in the fourth wave of the pandemic, even two full doses of the vaccine do not guarantee 100% protection against infection. A breakthrough infection is very similar to being normally infected with corona, but there are important differences.
A study of corona symptoms shows that the five most common symptoms among vaccinated people infected with corona are: headache, runny nose, sneezing, sore throat and decreased sense of smell.
This sounds like the usual and well-known symptoms that the unvaccinated experience.
But without the vaccine, there are two other symptoms that the vaccinated are spared: fever and persistent cough.
A study comparing symptoms among vaccinated and unvaccinated individuals showed that a vaccinated person infected with corona had a 58% lower chance of developing fever. Most people who were vaccinated and then infected said they felt more like they had less colds.
Another difference is the risk of being admitted.
The vaccinated have a much lower chance of being hospitalized because of their symptoms and are less likely to suffer from long-term symptoms, often referred to as long-term COVID.
What increases the risk of infection in vaccinated people?
A study in the UK showed that the infection rate for the vaccinated is 0.2%, which means that one in 500 people is infected even though they have been vaccinated.
1 – Type of vaccine
The clinical trials conducted prior to the approval of the various vaccines, as well as the data collected after the start of the global population vaccination campaign, gave each of the approved vaccines a score in terms of the relative reduction of infection.
For Pfizer, which is most common among Israelis, the vaccine is 95% effective in reducing infection. Modern vaccine is very close, with 94% efficacy.
2 – Time elapsed since the last dose was received
3 – Variants
The virus we are dealing with today is not quite the same one that broke into our lives almost two years ago. There are rather new and sometimes slightly upgraded versions of it.
Certain mutations that the virus underwent during its worldwide travels brought us a number of variants, which are now being named with Latin letters in the alphabet. The Delta variant and its descendants have become the most dominant virus strain in most of the world.
The efficacy percentages of the vaccines were calculated at the experimental stage compared to the original version of the virus. However, once they were approved and administered, the vaccines were asked to defend themselves against slightly different versions of the virus.
Thus, the efficacy rates of Pfizer’s vaccine, which was 95% against the original virus, fell slightly to 93% against the Alpha variant and to 88% against Delta.
4 – Your immune system
All data mentioned in this article and in the studies it cites refer to the average risk relative to the general population. It is important to remember that each of us is an individual case, and the risk of each person becoming infected is the result of a complicated equation consisting of the type of vaccine received, how many doses were taken and when, and a person’s chances. to get the virus based on their lifestyle. For example, doctors or teachers are often in situations where their chances of getting the virus are higher.
But the strength of an individual’s immune system also plays a role.
The strength of the immune system usually decreases with age. In addition, chronic or prolonged medical conditions may weaken the immune response. This is why the elderly and those who are immunosuppressed tend to develop fewer antibodies after being vaccinated and are considered to be more vulnerable to infection.
In most countries, these groups have been given priority in vaccination, which means that they have been vaccinated in the earlier stages to protect them. But it also means that their immune system starts to decline faster.