Antibody and T-Cell responses elicited by different SARS-CoV-2 vaccines in Botswana: durability and impact of HIV infection and previous SARS-CoV-2 and prevalent infection

The rapid spread of SARS-CoV-2 variants of concern (VOCs) that have accumulated mutations able to evade the complex immune system response generated by vaccination or prior infection has caused several distinct waves around the globe.  The rapid unprecedented development of SARS-CoV-2 vaccines has had the biggest impact on the fight against the COVID-19 pandemic. Botswana has had a good SARS-CoV-2 vaccine rollout and is one of the best-performing countries in Africa. The vaccines that have been included in the Botswana Covid-19 vaccination programme are quite diverse including AstraZeneca, Sinovac, Johnson & Johnson, Pfizer, and Moderna vaccines. These vaccines are some of the most used globally and in the African region. There is, however, limited data on the efficacy of these vaccines in a real-world setting in Africa. Botswana and most of sub-Saharan Africa have the distinction of being the region with the highest prevalence of HIV. A number of studies have shown that people living with HIV individuals are more likely to have severe COVID-19 compared to HIV-uninfected individuals.  HIV infection is as well associated with reduced vaccine efficacy and vaccine-associated immune responses. It is therefore important to carry out studies on the vaccine efficacy in African settings as, given the unique prevailing conditions, the vaccines might have different efficacy in this population. Simani Gaseitsiwe and Sikhulile Moyo’s study will determine the  magnitude, quality, and durability of SARS-CoV-2 vaccines elicited immune responses – both antibody responses and T-cells in individuals in Botswana who were vaccinated with different vaccines: AstraZeneca, Sinovac, Pfizer, and Johnson & Johnson. The impact of HIV infection on the vaccine-elicited immune responses will also be investigated. The durability of the vaccines elicited responses will be monitored by comparing the immune responses at different times post-vaccination. The levels of binding and neutralising antibodies will be compared by vaccine received and by HIV status. The antibody levels will also be compared by previous SARS-CoV-2 infection. 

So far, Gaseitsiwe and Moyo have observed that immune response (SARS-COV-2 Anti-S) decline with time since vaccination, declines vary by vaccine product but did not differ by HIV status. They observed that  history of natural SARS-CoV-2 infection and COVID-19 vaccination was associated with higher levels of Anti-S responses. Their data will help to identify which vaccine product has the greatest magnitude of immune responses and the longest lasting immunity. These would be the products that would be recommended for use in Botswana. Also, results show that HIV infection does not impact vaccine efficacy in the context of SARS-CoV-2 vaccination and as such, there is no need for a separate vaccination policy for people living with HIV.

Going forward, the need to understand the long-term impact of the COVID-19 vaccines remains very important given the possibility of re-emergence of variants of concern; this work will contribute to future improvement to the vaccines for SARS-CoV=2; and understanding of the impact of HIV infection on vaccine responses/efficacy in general should remain an important area of research, especially in sub-Saharan Africa where HIV prevalence is high.