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Follow-up research provides key insights into the effectiveness of the COVID-19 vaccine
By the staff editors of HospiMedica International
Posted on August 03, 2021
Large-scale follow-up studies conducted in people vaccinated with the Pfizer-BioNTech COVID-19 vaccine have shed new light on the lifespan of antibodies, the effects on patient types and efficacy against the Delta variant.
Israel, which has been at the forefront of vaccinating its citizens, has also conducted extensive follow-up studies on the effects and efficacy of the Pfizer-BioNTech COVID-19 vaccine.
In an analysis of more than 26,000 blood samples, researchers at Tel Aviv University (Tel Aviv, Israel) and Shamir Medical Center (Be’er Ya’akov, Israel) found that the levels of antibodies COVID-19 vary by age and gender. Their study found that symptomatic women infected with COVID-19 had the strongest immune response after age 50, while symptomatic infected men had the strongest immune response at around age 35. . Scientists attributed these differences to hormones. The researchers also found that the vaccinated people had an immune response four times stronger than the COVID-19 patients who had recovered.
In another study of 17 hospitals, researchers at Samson Assuta Ashdod Hospital (Ashdod, Israel) found that older people who suffered from several underlying health conditions and immunosuppression were more prone to it. SARS-CoV-2 and severe COVID-19 infection despite being fully vaccinated.
A team led by Sheba Medical Center (Ramat Gan, Israel) also undertook a study to determine whether mRNA vaccines such as Pfizer’s had a negative impact on fertility. Their study found that fully vaccinated couples had no difference in sperm quality, semen volume, ovarian stimulation, or the proportion of high-quality embryos compared to their IVF cycles before vaccination. Likewise, a study from the Hadassah-Hebrew University Medical Center (Jerusalem, Israel) found that the COVID-19 vaccine had no effect on sperm parameters.
Another study conducted by Sheba Medical Center in collaboration with the Institut Pasteur (Paris, France) and Sorbonne University (Paris, France) found that among all vaccinated members living in the same home, the risk of contracting COVID-19 for any household member decreased from 57% to 4%. Even a single household member inoculated with the Pfizer vaccine significantly reduced the risk to unvaccinated household members. This confirmed the results of an earlier study which indicated that fully vaccinated individuals appeared to benefit from protection against COVID-19 even after being exposed to infected family members.
The effectiveness of the Pfizer COVID-19 vaccine in preventing infections and symptomatic illnesses fell to 64% in early July, from a high of 95% reported in May by the Israeli Ministry of Health. This can be attributed to the entry of the Delta variant into the country. The same ratio fell further to around 40% according to a report released on July 22, most likely due to the effects of vaccinations given in January and February wearing off over time. The early July report said the vaccine was 93% effective in preventing serious illness from COVID-19, while the figure in the late July report showed a 91% drop in effectiveness. In addition, the ministry also found that there was a one-third less chance that healthy vaccinated people would develop severe COVID-19 compared to healthy unvaccinated people.
These results were confirmed by an analysis of the medical records of tens of thousands of members of the Israeli Health Fund HMO Leumit which indicated that people who had been vaccinated before the end of February were at double the risk of a revolutionary infection with the virus. SARS-CoV-2 in relation to people. vaccinated since the end of February. However, it could not be confirmed whether this was due to the fact that the majority of those vaccinated early were the elderly and / or people with chronic health conditions, or because of the decreased effects of the Pfizer vaccine. .
A panel of Israeli researchers reported to the Health Ministry that rare cases of myocarditis, an inflammation of the heart muscle, have been seen in men under 25 who took the second dose of Pfizer-BioNTech COVID-19 vaccine . However, the majority of cases were mild and resolved within a few weeks. At the end of July, the Ministry of Health reported that 80% of vaccinated people who suffered infection with COVID-19 did not infect people they came into contact with in public places.
Studies conducted at the start of Israel’s vaccination campaign found that the immunity of the Pfizer-BioNTech COVID-19 vaccine was highest 14 days after the first of two doses was given. The results also showed that people infected after taking the first dose had a significantly lower risk of passing the virus on to others. Additionally, the first dose of the vaccine has been shown to boost immunity even in people who have recovered from COVID-19.
In another study, Sheba Medical Center employees who took both doses of the Pfizer vaccine were found to have higher levels of antibodies to SARS-CoV-2 compared to people who recovered from COVID- 19. Meanwhile, a small study at Tel Aviv Sourasky Medical Center (Tel Aviv, Israel) found antibodies produced in the breast milk of nursing mothers who were fully vaccinated, potentially protecting their babies. In other findings, a study conducted in February showed that people who received the Pfizer-BioNTech COVID-19 vaccine were significantly less likely to “reject” or pass on viral particles present in their nose or throat.
Another important study from Sheba Medical Center showed that among 11,453 fully vaccinated health workers in the medical center, 39 breakthrough cases of COVID-19 were detected by RT-PCR tests of 1,497 of the workers vaccinated between Jan. 20. and April 28. Of those 39 groundbreaking COVID-19 cases, the suspected source of infection was an unvaccinated person in 37 cases. None of the infected workers required hospitalization, although 19% reported having long symptoms of COVID-19 six weeks after their diagnosis, including prolonged loss of smell, persistent cough, fatigue, weakness, dyspnea, or myalgia.
The results of the above study appeared in the online publication ISRAEL21c, which featured a summary of the scientific findings that were reported between January and July 2021.
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