Following a period of relative remission of the COVID-19 pandemic, the recent spread of the SARS-CoV-2 delta variant has led to a new outbreak of cases even in countries with fairly satisfactory vaccination rates, which of course were far from universal vaccination of the entire population. . In this light, it is important to determine the real potential and potential protection of vaccines against SARS-CoV-2. The Doctors of the Therapeutic Clinic of the Medical School of the National and Kapodistrian University of Athens Theodora Psaltopoulou, Giannis Danasis, Panos Malandrakis and Thanos Dimopoulos (Rector of EKPA) summarize the data of the recent publication of Arnold S Monto in the prestigious scientific review The New England Journal of Medicine (N Engl J Med 2021; 385: 1825-1827).
Primary clinical trials of SARS-CoV-2 mRNA vaccines have shown the high protection they offer against laboratory-confirmed COVID-19 disease. In addition, the protection they offer against asymptomatic disease is important. This is because it is known that most vaccines against viral infections mainly prevent symptomatic infection rather than asymptomatic carriers. Naturally, these results revived hopes that the vaccine could prevent the transmission of SARS-CoV-2 from person to person and thus the pandemic would begin to decline until it was completely eradicated. However, the emergence and prevalence of new SARS-CoV-2 strains with increased transmission potential, such as the Delta strain, combined with declining immunity over time have eliminated particularly promising approaches. Of course, it is known from virology that the eradication of a viral disease through collective immunity is most effective when the infectious agent has low transmissibility and there is not a large number of vulnerable individuals to the infection. Given the course of the SARS epidemic in 2002, the COVID-19 pandemic could be tackled specifically with the approval of vaccines. However, it is worth noting that the SARS epidemic was clearly more entrenched areas with mainly local epidemics, rather than the pandemic nature of COVID-19. Therefore, Dr. Monto believes that the influenza model can better help us predict the course of the COVID-19 pandemic and the role of vaccinations in the long run. A new influenza strain has the potential to pandemic and may burden the health system to a degree similar to SARS-CoV-2.
After months and several infectious waves, the new strain may remain as a new seasonal strain that may show antigenic changes – albeit to a lesser extent than SARS-CoV-2. The new strain is thus added to the flu strains that show seasonal variation. The purpose of the annual flu vaccine is to reduce the risk of serious illness and death from the flu and to prevent outbreaks as far as possible. Prevention of mild illness is not a fundamental goal of influenza vaccination. The necessity of the annual flu vaccine lies in the reduction of the immunity offered by the vaccine over time as well as in the emergence of new strains of influenza every year. It is worth noting that the effectiveness of the flu vaccine does not exceed 60% at best, and therefore the main goal is to prevent serious infections and complications of the flu. In contrast, the efficacy of the vaccine against SARS-CoV-2 is clearly higher. However, the predominance of new strains may reduce the effectiveness of vaccination.
It is now quite certain that booster doses of the SARS-CoV-2 vaccine will need to be given in proportion to the booster doses of the flu virus. It is, of course, clear that the interval between COVID-19 booster doses should be clearly defined. An important challenge is also to adapt the vaccines according to the prevailing strains of SARS-CoV-2 in each time period, in order to ensure the high efficiency of the vaccination. Asymptomatic and mild infections may continue to occur in vaccinated patients, but the key to the success of the vaccination program will be the reduction of hospitalizations and deaths due to COVID-19. At the same time, it is particularly important to continue research into potent antiviral agents in order to optimize the treatment of patients with COVID-19 independently of the SARS-CoV-2 executive. In conclusion, Dr. Monto concludes that, although we can not accurately predict the course of the pandemic, humanity will learn to live with COVID-19, as it has learned to live with the flu.
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