On Thursday, results from a six-year clinical trial for the vaccine – the largest study of its kind – showed it reduced the infection rate by 31 per cent. The US military study took place in Thailand, where the prevalent strains of HIV are subtypes B and E. The B strain of the virus is the same one found in Europe and North America.
However, it’s different from the HIV strain plaguing Rwanda, subtype A, which accounts for about 90 per cent of the country’s infections. Rwanda’s other 10 per cent of HIV cases are said to be caused either by the subtype C or a mutation of the two strains.
The C strain of the virus is also responsible for the majority of HIV infections in southern and eastern Africa, as well as India.
Dr. Anita Asiimwe, executive secretary of the government-run National AIDS Control Commission (CNLS), welcomed the study results but immediately noted the vaccine may be ineffective against HIV virus found here.
“It’s not for the strain that’s in Rwanda,” Asiimwe said. “For us, it’s not a complete answer.”
However, she said, the clinical trial results are still “good news” because it shows a vaccine is possible, and could be developed for other strains once scientists understand why it’s effective.
“The science behind it is the same, so if we’ve seen some success for other strains it means there is hope,” Asiimwe said.
For Dr. Michael Kramer, director general of TRAC Plus, the national centre for infectious diseases control and prevention, there is no proof the vaccine would protect Rwandans.
However, he did not appear to be overly discouraged by the fact. “You have to start somewhere,” he said.
Further research could reveal the new vaccine is effective against the HIV strain in Africa, or it could show that separate vaccines are needed for different subtypes of the virus.
“This is more like a proof of principle,” Kramer said. “This news is exciting in that there seems to be a way.”
Kramer added that a 31 per cent efficiency rate, which the study’s researchers labeled as ‘moderately effective,’ is very low for a typical vaccine.
Most vaccines are usually considered to be 85 to 95 per cent effective, he said.
However, Kramer said, if researchers are unable to increase the vaccine’s efficiency, it could be distributed as a partial vaccine as long as it were used with other preventative measures such as male circumcision, male or female condoms, and early treatment of sexually transmitted infections.
But he warned that if a partial vaccine were licensed, patients would need to fully understand they were still at risk for contracting the virus.
He said experiences with other partially-effective prevention measures, like circumcision, have shown that people may actually engage in riskier behavior because they falsely believe they’re immune to the virus.
He added the next step for researchers is to cautiously review the Thailand study’s data and hammer out exactly why the vaccine proved effective in some cases.
In a joint statement, the World Health Organization and the United Nations Programme on HIV/AIDS stressed the need to determine how the HIV vaccine will interact with other strains.
“It remains to be seen if the two specific vaccine components in this particular regimen would be applicable to other parts of the world with diverse host genetic backgrounds and different HIV subtypes driving different regional sub-epidemics,” the statement read.
“Once an HIV vaccine does become available, it will need to be universally accessible by all persons at risk.”
According to information released by the U.S. Army – one of several American government agencies that funded the vaccine study – Thailand was chosen for the study because the country had “a severe, generalized HIV epidemic, and was one of the first countries to have developed a National AIDS Plan and a National HIV Vaccine Development Plan.”
Advocacy group ActionAid said while the vaccine study results are positive, treatment of current infections and combating the sexual violence against women that often leads to infections should remain the priority.
“Two-thirds of patients in Africa, a majority of whom are women and girls, still lack access to treatment and the human and economic cost of this shocking neglect is intolerably high,” Anne Jellema, ActionAid’s international policy director, said in a statement.