As with other variants, the WHO recommended that people continue to keep enclosed spaces well ventilated, avoid crowding and close contact, wear well-fitting masks, clean hands frequently, and get vaccinated. ;Response by vaccine producers On 26 November 2021, BioNTech said it would know in two weeks whether the current vaccine is effective against the variant and that an updated vaccine could be shipped in 100 days if necessary. AstraZeneca, Moderna and Johnson & Johnson were also studying the variant's impact on the effectiveness of their vaccines. On the same day, Novavax stated that it was developing an updated vaccine requiring two doses for the<unk>  variant, which the company expected to be ready for testing and manufacturing within a few weeks. On 29 November 2021, The Gamaleya Institute said that Sputnik Light should be effective against the variant, that it would begin adapting Sputnik V, and that a modified version could be ready for mass production in 45 days. Sinovac said it could quickly mass-produce an inactivated vaccine against the variant and that it was monitoring studies and collecting samples of the variant to determine if a new vaccine is needed. On 7 December 2021, at a symposium in Brazil with its partner Instituto Butantan, Sinovac said it would update its vaccine to the new variant and make it available in three months. On December 2, the Finlay Institute was already developing a version of Soberana Plus against the variant. Pfizer hopes to have a vaccine targeted to immunize against<unk>  ready by March 2022. ;WHO On 29 November 2021, the WHO said cases and infections are expected among those vaccinated, albeit in a small and predictable proportion. ;Vaccine efficacy In December, studies, some of which using large nationwide datasets from either Israel and Denmark, found that vaccine effectiveness of multiple common two-dosed<unk> ID-19 vaccines is substantially lower against the<unk>  variant than for other common variants including the Delta variant, and that a new (often a third) dose – a booster dose – is needed and effective, with it i.a. substantially reducing deaths from the disease compared to cohorts who received no booster but two doses. On 7 December 2021, preliminary results from a laboratory test conducted at the Africa Health Research Institute in Durban with 12 people who received the Pfizer-BioNTech vaccine found a 41-fold reduction in neutralizing antibody activity against the variant in some of the samples. This is a big reduction, but it does not mean that the variant can escape vaccines completely, so vaccination with current vaccines is still recommended. Neutralizing antibody activity against the variant was greater in those fully vaccinated after being infected about a year earlier. Effectiveness estimates will likely change as more data is collected, as antibodies generated by vaccination vary widely between individuals and the sample was small. On 8 December 2021, Pfizer and BioNTech reported that preliminary data indicated that a third dose of the vaccine would provide a similar level of neutralizing antibodies against the variant as seen against other variants after two doses. On 10 December 2021, the UK Health Security Agency reported that early data indicated a 20- to 40-fold reduction in neutralizing activity for<unk>  by sera from Pfizer 2-dose vaccinees relative to earlier strains and a 20-fold reduction relative to Delta. The reduction was greater in sera from AstraZeneca 2-dose vaccinees, falling below the detectable threshold. An mRNA booster dose produced a similar increase in neutralising activity regardless of the vaccine used for primary vaccination. After a booster dose (usually with an mRNA vaccine), vaccine effectiveness against symptomatic disease was at , and the effectiveness against severe disease was expected to be higher. In January 2022, results from Israel suggested that a 4th dose of vaccine is only partially effective against the<unk>  strain. Many cases of infection broke through, albeit "a bit less than in the control group", even though trial participants had higher antibody levels after the 4th dose. ;WHO recommendations for epidemiology On 26 November 2021, the WHO asked nations to do the following: * Enhance surveillance and sequencing efforts to better understand circulating SARS-CoV-2 variants. * Submit complete genome sequences and associated metadata to a publicly available database, such as GISAID. * Report initial cases/clusters associated with virus-of-concern infection to WHO through the IHR mechanism. * Where capacity exists and in coordination with the international community, perform field investigations and laboratory assessments to improve understanding of the potential impacts of the virus of concern on<unk> ID-19 epidemiology, severity, and the effectiveness of public health and social measures, diagnostic methods, immune responses, antibody neutralization, or other relevant characteristics.
SARS-CoV-2 Omicron variant
SARS-CoV-2 Delta variant
SARS-CoV-2 Epsilon variant
SARS-CoV-2 Alpha variant
SARS-CoV-2 Gamma variant
SARS-CoV-2 Eta variant
SARS-CoV-2 Lambda variant
SARS-CoV-2 Mu variant