COVID-19 Vaccine Updates for People Under Different Conditions

This review is led by Prof. Bin Cao and Dr. Zai Wang from China-Japan Friendship Hospital. The co-first authors are Yijiao Huang, a graduate student of Tsinghua University School of Basic Medicine, and Weiyang Wang, a graduate student of Peking Union Medical College, Chinese Academy of Medical Sciences.

By January 2024, a total of 13.59 billion doses of the COVID-19 vaccine had been administered. However, the high mutation rate of the virus weakens the effectiveness of the original vaccines in preventing breakthrough infections. In the current era of the omicron epidemics, do people still need to be vaccinated after already being infected with COVID-19 at least once? And if so, what type of vaccine is the most effective? These are common concerns among the public. Specifically, elderly individuals, those with chronic diseases, or special populations with compromised immune function comprise a significant portion of COVID-19 patients and may be at a higher risk for severe illness. "Determining the appropriate vaccination strategies for these special populations is a crucial issue that requires special attention," said Cao.

The review summarizes the efficiency of different vaccines in clinical trials and their effectiveness in the real world. In clinical trials, different vaccines have shown an overall efficiency ranging from 66% to 96%. However, in real-world observations, the effectiveness of vaccines is higher in the early stages of use but significantly decreases during periods when variants such as Omicron are prevalent. Nevertheless, complete vaccination and booster injections can still significantly reduce the infection rate and disease severity, while also providing protection against the occurrence of long COVID. This fully indicates that vaccination has made a significant contribution to alleviating the global epidemic.

Currently, dozens of multivalent or monovalent vaccines targeting mutant strains have completed clinical trials, which may have better protective efficacy against mutant strains. However, research has shown that the components targeting the original strain in multivalent vaccines may impair the production of antibodies against mutant strains, known as “original antigenic sin”. In addition, since early epidemic strains are no longer widely spread, currently only specific monovalent vaccines targeting epidemic strains are recommended.

For special populations such as the elderly, individuals with diabetes and obesity, those with chronic heart, lung, liver, or kidney disease, as well as those with inflammatory bowel disease, autoimmune disease, cancer, transplantation, primary immune deficiency, HIV, and other immune deficiencies, although the effectiveness of vaccines may decrease in these populations, multiple doses of vaccination can still elicit strong protective immune responses that greatly outweigh the potential risks. Therefore, for these special populations, ongoing vaccination and booster shots are important measures to reduce the risk of severe illness and death.

It should be noted that for those who suffer from autoimmune diseases or are prone to inflammatory reactions, caution should be exercised when administering vaccines such as mRNA vaccines that may trigger strong immune reactions. However, there are no restrictions on administering inactivated vaccines. In addition, although pregnant women are not susceptible to severe COVID-19, in view of the higher risk of adverse pregnancy and birth after infection with COVID-19, it is strongly recommended that pregnant women be vaccinated and given booster injections at any time during pregnancy. Compared to the above population, the priority of vaccination for children is relatively low. However, considering the crucial role of children in virus transmission, vaccination is still recommended.

In summary, this review comprehensively examines the effectiveness, research and development status, and use of the COVID-19 vaccine in people under different conditions. “We hope that this review can address any doubts that the public, especially special populations, may have regarding vaccination. It is hoped that they can utilize optimized vaccination strategies to more effectively prevent potential serious COVID-19.” said Cao.

See the article:

COVID-19 vaccine updates for people under different conditions

https://doi.org/10.1007/s11427-024-2643-1

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