The two basic properties of Omicron variant, the great transmissibility and the immune escape related to the vaccine effectiveness, as the latest data on the effectiveness of the third dose in preventing severe illness and death indicated that Maria Theodoridou, Chair of the National Vaccination Committee during the briefing on the National Vaccination Coverage Plan for the disease COVID-19.
The effectiveness of the third dose in reducing infections is on the order of 50% and «it is precisely the fact that has disappointed us that The vaccine can't build a wall and stop transmission. »However, according to the FDA, 50% is a criterion for classifying a vaccine as effective," Ms. Theodoridou emphasized.
According to data from a study conducted in the United Kingdom, administration of the third dose prevents death at a rate of 95% after two weeks, whereas with two vaccine doses, after 25 weeks, the rate is 59%. In other words, even with the Omicron variant, the third dose achieves the same rates we saw with the Delta variant, he noted.
The effectiveness in preventing hospitalizations is demonstrated by three different studies. The reduction in hospital admissions with two doses after 4–6 months ranges from 44 to 68%, while with three doses, the effectiveness ranges from 83 to 90% and lasts for more than three months.
The role of the booster shot is twofold, Ms. Theodoridou emphasized. To increase the chemical immunity and, at the same time, the B and T lymphocytes that represent the cell-mediated immunity, which is important for the ‘Omicron” variant, since protects against serious illness. Countries with high vaccination rates have an increased number of cases but a low number of severe infections, whereas, conversely, in the United States, where vaccination rates are low, there has been an increase in hospital admissions.
Ms. Theodoridou also mentioned the administration of the fourth vaccine dose, emphasizing that Scientists around the world are skeptical about the possibility of administering a fourth dose. He noted that Israel has begun administering a fourth dose and has observed a decline in the number of cases, which is to be expected, but we will see the results regarding the prevention of severe infections and deaths in the coming period.
The WHO states that increasing the doses of the initial vaccines will not be the solution to halting the emergence of new variants. The big challenge, he emphasized, is developing vaccines that will stop the transmission of the virus and provide broad and long-lasting protection.
As long as global vaccination rates remain low, we cannot afford to be complacent about bringing the pandemic under control, Ms. Theodoridou emphasized.
Finally, he referred to the long-covid syndrome, which has drawn the concern and interest of scientists and where, according to scientific data, vaccination reduces the likelihood of its occurrence. Post-COVID syndrome, as he said, has an unknown pathogenesis that is likely due to an inflammatory response in the individual and appears at least 4 weeks after infection, with symptoms including fatigue, difficulty breathing, loss of smell and taste, and cognitive impairment.
Data from the United Kingdom based on self-reports recorded 1,266,000 people with symptoms similar to those of long COVID. It was found that between 3 and 12% percent of individuals still had symptoms after 12 weeks.
Data from England indicate that people who have received two doses of the vaccine are 50% less likely to develop this syndrome.
