Vaccine candidate reduced household transmission of SARS-CoV-2: Study

A new study in Clinical Infectious Diseases provides additional data from SPECTRA, a global Phase 2/3 clinical trial, that showed vaccination with SCB-2019 (CpG 1018/Alum) reduced the risk of transmitting SARS-CoV-2 infection to household members, compared to placebo participants.

"These results are important for public health officials striving to control future outbreaks and indicate that vaccination with SCB-2019 considerably reduces the risk of SARS-CoV-2 spreading within communities," said Dr. Nicholas Jackson, President of Global Research and Development of Clover Biopharmaceuticals. "The new data on community-level impact further strengthens our confidence in SCB-2019 as a premier vaccine that can potentially play an important role in large-scale vaccination campaigns in China and globally."

The study demonstrated that a household contact was 84% less likely to get a SARS-CoV-2 infection when the infected household member had received SCB-2019, compared to households where the infected household member was not vaccinated. Among the 134 household contacts of infected household members who had received SCB-2019, there was one case of COVID-19; among the 250 household contacts of infected household members who were not vaccinated, there were 12 cases.

"As the world grapples with new outbreaks and variants, IVI is proud to advance our scientific understanding of the benefits of COVID-19 vaccination beyond personal protection," said Jerome Kim, MD, Director General of the International Vaccine Institute. "The clear takeaway from this study with Clover's SCB-2019 is that vaccines with demonstrated safety and efficacy can reduce the risk of household transmission and should continue to play a central role in the ongoing global response strategy to COVID-19."

There were no cases of symptomatic SARS-CoV-2 infection among household contacts who were partially or fully vaccinated and where the infected household member was vaccinated with SCB-2019. This indicates that SCB-2019 vaccination reduced household transmission and that vaccinated household contacts also likely benefited from the protection provided by their own vaccination.

This exploratory, prospective study was part of the SPECTRA Phase 2/3 trial and compared reductions in SARS-CoV-2 inflections in households and household contacts of SCB-2019 vaccine recipients with infections in households and household contacts of placebo recipients. The study was performed at eight Phase 2/3 SPECTRA sites in the Philippines.

A total of 154 participants who received placebo or SCB-2019 and who subsequently experienced SARS-CoV-2 infection were enrolled in this study as were 388 of their household contacts. The study team was blinded to the assignment of SPECTRA participants to vaccine or placebo groups.

Enrolled households and household contacts were monitored for three weeks to detect new COVID-19 infections. Symptomatic cases for participants and household contacts were confirmed with reverse transcriptase polymerase chain reaction (rRT-PCR) test, while asymptomatic cases were determined using anti-N antibody rapid antibody test kits.