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Juan Rodriguez (L), reacts to Johnson & Johnson's Janssen Covid-19 vaccination administered by Christina Garibay, a vocational nurse at Skid Row. Christina Garibay offered Covid-19 testing and vaccines in Los Angeles on August 22, 2021. Frederic J. AFP
Experts say that Covid-19 vaccines remain "stunningly efficient" despite concerns that immunity might wane over time. Recent studies have raised concerns about the effectiveness of Covid-19 vaccines. These were prompted by a rising number of Covid cases in fully vaccinated people. However, studies have shown that fully vaccinated people are still protected from severe infection, hospitalization, and death due to the virus. The Israeli government published preliminary data in July that showed that only 16% of people who received two doses of the Pfizer vaccine in January were protected against symptomatic infections. The vaccine was 79% effective against symptoms in people who were fully vaccinated by April. This suggests that immunity acquired through immunizations diminishes over time. Pfizer funded research published in July showed that the Pfizer BioNTech vaccine's efficacy was highest between one and two months after the second dose. It came in at 96.2%. However, it declined by an average 6% every 2 months. Its effectiveness dropped to 84% approximately four to six months after the second dose. A U.K. study that included more than one million people vaccinated found that both the Oxford-AstraZeneca as well as the Pfizer BioNTech vaccines had progressively decreased in effectiveness over time. The analysis revealed that protection against the virus was 88% a month after the second dose of Pfizer vaccine. This protection dropped to 74% after five to six months. After being fully vaccinated with Oxford-AstraZeneca, protection was at 77% per month. It dropped to 67% within four to five months.
Lessons from Israel
Israel's vaccination program was among the fastest in the globe. However, Covid-19 cases have been on the rise in Israel since July.
Israel started offering a third dose of vaccines to everyone over 60 in July. The country's booster program was rapidly expanded, and since August third shots have been made available to all over 30 years old. Professor Eyal, an infectious disease specialist at Sheba Medical Center, said that although cases are rising despite high vaccination rates, severe illnesses in Israel remained "substantially lower." He said that the reason for this is that the majority of the country's adult population has been vaccinated with two doses and that more than one million have received the third booster. Leshem said that the severe disease rates among the vaccinated is about one-tenth that of the unvaccinated. This means that the vaccine is still more than 90% effective in preventing severe diseases. Our short-term data show that people who have received the booster dose are at a much lower risk of getting infected. Richard Reithinger is an infectious disease expert who is also vice president global health at RTI International in the United States. He told CNBC via email that the majority of vaccines for Covid-19 have been "stunningly effective," even with newer variants. He said that there was clear evidence that severe diseases such as those that require hospitalizations and deaths dropped dramatically in countries with high vaccination coverage. "In countries with high vaccination coverage like Iceland, which has more than 90%, there are very few severe cases or deaths. Similar results can be seen in countries with high levels of vaccine coverage like Canada and the U.S., where severe cases and death are almost always reported by the unvaccinated.
Delta effect
A May English study published by Pfizer-BioNTech found that the vaccine was 88% effective in preventing symptoms from the delta variant. The vaccine was 93% effective against the alpha variant, which was once the dominant strain in Britain. The research also found that Oxford-AstraZeneca vaccine was 60% more effective in preventing symptoms from the delta variant than the 66% rate for the alpha variant. This study showed that the efficacy rate of the two vaccines against symptoms from the delta variant was only 33% after the second dose. CNBC's Reithinger said that even if the virus continues to evolve, it didn't necessarily mean that it would become more resistant. The delta variant is more transmissible than the other variants and vaccine effectiveness is slightly lower that for the beta and alpha variants. He also highlighted that the kappa variant which was discovered in India at the same time is not as transmissible.
Are booster shots the solution?
Many other countries, including the U.S., offer or plan to offer third doses Covid-19 vaccines in order to boost immunity against the virus that may be depleted. Gideon Schreiber from Israel's Weizmann Institute of Science says booster shots could become a necessity. He predicted that booster shots would not be required every year, but twice annually. "The virus is susceptible to new variants. Many of these will suppress immunity, so we may need boosters in the future." Schreiber said that Israel's booster program had been a huge success so far. He said that people became four to five times less likely after a second dose of Covid. However, people were ten times less likely than before to contract the virus after taking a third dose. Reithinger said that booster shots are not a necessary step at this time. He told CNBC via email that there is limited evidence that the immune response that was triggered by vaccines has waned after six to eight month. "Most of this data is focused on infection rather than hospitalization and death. Data also don't include non-pharmaceutical interventions such as social distancing and masking. These should be continued to be used in many situations. Only the immunocompromised are the only population for whom booster shots may be justified. He said booster shots could become necessary in the future if there is no data to support their effectiveness against severe diseases and death.
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