'Infection from a Single Drop of Saliva' Omicron... "Outside the House is More Dangerous" [Reading Science]

[Asia Economy Reporter Kim Bong-su] The Omicron variant, which can infect with just a single droplet of saliva, has been found to have relatively stronger transmissibility outside the home, such as in workplaces, compared to the Delta variant.

A research team from the UK Health Security Agency recently investigated 51,281 patients confirmed with Omicron or Delta variants and their 151,592 close contacts between December 5 and 12 last year. According to the international academic journal Nature on the 5th, the Omicron variant was found to spread more effectively outside the home compared to the previous Delta variant.

The study compared the transmissibility of the two variants inside the home and outside, such as in workplaces. Within households, the Delta variant was transmitted to 11% of family members living with the confirmed patient. In contrast, the transmission rate among family members of Omicron patients was about 16%. This confirmed that the transmissibility of the Omicron variant is approximately 48% higher than that of the Delta variant.

However, the difference in transmissibility between the two variants was more pronounced outside the home, such as in workplaces. The transmission rate of the Delta variant was 4%, while Omicron's was 8%, more than double. A research team official explained to Nature, "The Omicron variant has the advantage of infecting more effectively outside the home compared to the Delta variant," adding, "Omicron's infectivity is more than twice that of Delta, so infection can occur even without repeated or prolonged exposure."

The research team also examined the impact of vaccination on the transmissibility of the two variants. The results showed that among unvaccinated individuals, 23% more people were infected with Omicron than with Delta. Conversely, among vaccinated individuals, the immune evasion ability of Omicron was evident. When investigating family members who had received the third dose (booster shot), the probability of Omicron infection was twice as high as that of Delta. The transmissibility to others was similarly about twice as high.

The research team also found the effect of the booster shot. Compared to those who had received two doses, the probability of Delta infection was 32% lower, and the probability of Omicron infection was 12% lower. Transmission to family members was also reduced by 38% for Delta and 22% for Omicron compared to those who had completed two doses.

A research team official emphasized, "These study results suggest that existing COVID-19 vaccines provide limited but some protection against Omicron variant infection," adding, "The vaccines have also been proven to prevent severe illness from both Delta and Omicron variants. While additional research is needed on the stealth Omicron variant, vaccines remain the most important means to reduce mortality and severity rates at present."