The rollout of Russia’s Sputnik V Covid-19 vaccine in South Africa has been put on hold for now.
The South African Health Products Regulatory Authority (Sahpra) says it has decided not to approve the vaccine in its current form after research showed that vaccinated men are at risk of getting HIV.
Sahpra has been engaged in a rolling review of the data for the Sputnik V Covid-19 vaccine since the initial application was submitted in February.
Vaccine trials in America and South Africa
The safety of adenovirus vaccine vectors has been the subject of several studies.
The Step trial primarily used gay men in the Americas, while the Phambili trial in South Africa used heterosexual men and women.
Both clinical trials were designed to administer three doses of an Ad5-vectored vaccine encoding the HIV gag, pol and nef proteins.
“In both the Step and Phambili trials, administration of an Ad5-vectored vaccine was associated with enhanced susceptibility/acquisition of HIV in men,” said Sahpra CEO Dr Boitumelo Semete-Makokotlela.
The vaccine was developed by the Gamaleya Research Institute of Epidemiology and Microbiology in the Russian Federation, and the locally licensed applicant is Lamar International.
Sahpra then asked Lamar International to provide data demonstrating the safety of the Sputnik V vaccine in settings of high HIV prevalence and incidence.
“The applicant was not able to adequately address Sahpra’s request,” said Semete-Makokotlela.
“Sahpra is concerned that the use of the Sputnik V vaccine in South Africans, with a high HIV prevalence, may increase the risk of vaccinated males acquiring HIV,” she added.
Long road to Sputnik V
The Step trial ended in September 2007 due to lack of efficacy. Still, evidence quickly emerged of an enhanced risk of HIV infection in uncircumcised men with high titers of pre-existing antibodies to Ad5.
The increased risk of HIV among vaccine recipients became statistically significant when the entire trial population was analysed.
“During the application for approval assessment of the Sputnik V vaccine, Sahpra reviewed the outcomes of the Step and Phambili trials in detail, including arguments by Lancet in 2020, said Semete.
The regulatory body also consulted expert committees, including leading local and international scientific community members, on Russia’s vaccine.
The Sputnik V Covid-19 vaccine has not received Emergency Use Listing by the World Health Organization (WHO).
The most recent WHO update indicates that the process is “on hold, awaiting completion of rolling submission”.
The Sputnik V vaccine combines two separate adenovirus-vectored constructs as the delivery vehicles for the antigen.
One relies on Adenovirus Type 26 (Ad26) and the other on Adenovirus Type 5 (Ad5).
There have been concerns about the safety of Ad5-vectored vaccines in populations at risk for HIV infection.
One of the challenges faced by such vaccines is the presence of pre-existing Ad-specific neutralising antibodies (NAbs) in the general population.
The rolling review of the Sputnik V vaccine will remain open for submission of relevant safety data in support of the application.
Compiled by Narissa Subramoney