Many are concerned about reports of COVID-19 after being fully vaccinated. The good news is that most of these diseases are usually mild or asymptomatic, which shows that vaccines protect us from severe illness and death.
People who get sick after being vaccinated can continue to infect others . Preliminary evidence suggests that immunized people may have high levels of the virus in their nose , potentially as high as unvaccinated people. However, if you are vaccinated, you will get rid of the virus faster by shortening the time during which you are infectious and can transmit the virus further.
Two studies from the United Kingdom show that the immunity we get from COVID-19 vaccines wanes over time, after about four to six months. While the more contagious Delta variant continues to circulate, the weakening of the immune system leads to more disease in vaccinated people. However, the efficacy of the vaccine is very high from the moment of introduction, so a gradual reduction due to attenuation will not have a significant impact on protection for some time.
Israeli data also shows that some vaccinated people are contracting COVID-19. But it must be borne in mind that vaccination in Israel began in December 2020, and the majority of the population was vaccinated in early 2021. Many of them have already had six months since they were fully vaccinated. Considering that most people in Israel are vaccinated, however, the majority (87%) of hospitalized patients are over 60 years old. This underscores what is known about adaptive immunity and vaccine protection – they decline with age. Therefore, vulnerable groups, such as the elderly, are expected to be the first to be at risk of disease as their immune systems weaken, as well as people whose immune systems are weakened. This will be an ongoing problem for all countries.
What would be alarming if we began to see a significant increase in the number of fully vaccinated people who have severe illness and who die, but they do not. Globally, the vast majority of people with severe COVID-19 are not vaccinated.
The weakening of the immune system means that additional doses will be required to strengthen the defense, at least for the next several years, while the virus continues to circulate at such high levels. Currently, vaccines have been modeled after the original Wuhan virus strain, rather than the Delta variant that currently dominates most of the world .
MRNA vaccines such as Pfizer and Moderna can be effectively updated to target common variants, in this case Delta. Thus, the third Delta-based immunization will “improve” as well as enhance the existing immunity for longer lasting protection.
If you are fully vaccinated and have only fleeting contact with a positive case, you are most likely not breathing a lot of the virus and therefore are less likely to develop symptomatic infection. However, if you are in the same room with a positive patient for an extended period of time, you can inhale a huge amount of the virus. This makes it harder for your immune system to fight.
This may be one of the reasons we see some healthcare workers getting sick after being vaccinated because they are exposed to high viral loads.
Can vaccinated children play a role?
Vaccines are not yet approved for young children (under 12 years of age), so we are seeing an increase in the incidence of the disease in children compared to older people. Early research before the advent of Delta showed that children do not significantly contribute to infection transmission.
More recent studies in populations with vaccinated adults, where Delta is the dominant virus, have shown that children can facilitate transmission . But it is possible that if you live with an unvaccinated child who has contracted COVID-19, you will be exposed for many, many hours a day, hence breathing in large amounts of the virus. The higher the viral dose, the more likely you are to get sick despite being vaccinated.
The potential slowdown in the incidence of illness after vaccination is one reason for the need to vaccinate children aged 12 to 15 and young children in the future, if current trials prove that they are safe and effective in this age group. Another way is to protect the children themselves and get closer to herd immunity (if possible).
As COVID-19 becomes endemic, which means it is spreading into the human population, we will need to constantly monitor the interaction between vaccines and the virus. The virus can start to burn out, but it is also possible that it can constantly evolve and evade vaccines, as the flu does