Chinese Vector Vaccine For COVID-19 Showed Low Efficacy In The Elderly

Chinese vector vaccine for COVID-19 showed low efficacy in the elderly

Scientists suggest that older people may need additional vaccinations.

Photo: China Global Television Network

Chinese scientists have published the results of the second phase of a clinical trial of a recombinant adenovirus vector vaccine against COVID-19 in The Lancet. The study itself was conducted in April and involved over 500 people.

Oxford COVID-19 Vaccine Shows Promising Results In Next Phase Of Research

The vaccine successfully stimulated the production of antibodies and T cells, and the scientists did not find any serious side effects.

Read the article

The vaccine, tentatively named Ad5-nCoV, is based on a pathogenic adenovirus. The gene of the SARS-CoV-2 virus is inserted into its genome. The adenovirus delivers the SARS-CoV-2 genes to the human body, and antibodies are produced to the corresponding coronavirus proteins in humans.

The main goal of the study was to assess the response of the immune system to the vaccine and determine the most appropriate doses to be used in the next phase. The next, third, phase of the study will have to show whether the vaccine protects against COVID-19 in real life.

“The second phase of the study provides more data on the safety and immunogenicity of the vaccine in a larger group of people than in the first phase,” said Professor Feng-Cai Zhu of the Chinese Center for Disease Control and Prevention, co-author of the study.

First vector vaccine for COVID-19 shows effect in early phase of human study

This is the first complete data published in a scientific journal on a clinical trial of a Chinese vaccine against SARS-CoV-2.

Read the article

No serious vaccine side effects were reported in this study. The main adverse events were pain at the injection site, fever, and weakness. In 95% of participants who received a high dose of the vaccine, scientists found the production of T cells or antibodies against the coronavirus. In the low dose group, they were found in 91% of the participants.

The study authors point out that participants who were immune to the adenovirus used to make the vaccine developed much poorer immunity to SARS-CoV-2. Only 52% of the study participants were found to be immune to adenovirus that existed before vaccination.

The older people are, the more often they have immunity against adenoviruses. Therefore, when using this vaccine, the immune system is the least developed in the elderly. The production of antibodies is especially affected.

The authors point out that older people are the most important group in need of protection from COVID-19. They do not exclude that people of age will need additional vaccination. Only new research can show whether this will help.