90% of new cases in the UK are Delta (Indian) variant
Confirmed cases of COVID-19 variants identified in UK
[Public Health England.] Novel genotyping tests are being used to detect the Delta (VOC-21APR-02) variant, giving a result for action within 48 hours. Data from these tests is available for the first time this week, as PHE figures show that cases have risen by 29,892 to 42,323. The data indicates that over 90% of new COVID-19 cases in the UK are now the Delta variant, which continues to show a significantly higher rate of growth compared to the Alpha variant.
Vaccines highly effective against hospitalisation from Delta variant
[Public Health England.] New analysis by PHE shows for the first time that 2 doses of COVID-19 vaccines are highly effective against hospitalisation from the Delta (B.1.617.2) variant. The analysis suggests: (1) the Pfizer-BioNTech vaccine is 96% effective against hospitalisation after 2 doses; (2) the Oxford-AstraZeneca vaccine is 92% effective against hospitalisation after 2 doses. These are comparable with vaccine effectiveness against hospitalisation from the Alpha [UK] variant. The analysis included 14,019 cases of the Delta variant – 166 of whom were hospitalised – between 12 April and 4 June, looking at emergency hospital admissions in England.
BNT162b2-elicited neutralization of B.1.617 and other SARS-CoV-2 variants
[Pfizer. Delta / Indian.] Here we report that 20 human sera, drawn 2 or 4 weeks after two doses of BNT162b2, neutralize engineered SARS-CoV-2 with a USA-WA1/2020 genetic background (a virus strain isolated in January 2020) and spike glycoproteins from the newly emerged B.1.617.1, B.1.617.2, B.1.618 (all first identified in India) or B.1.525 (first identified in Nigeria) lineages. Geometric mean plaque reduction neutralization titers against the variant viruses, particularly the B.1.617.1 variant, appear lower than the titer against USA-WA1/2020 virus, but all sera tested neutralize the variant viruses at titers of at least 40. The susceptibility of these newly emerged variants to BNT162b2 vaccine-elicited neutralization supports mass immunization as a central strategy to end the COVID-19 pandemic across geographies.
Naturally enhanced neutralizing breadth against SARS-CoV-2 one year after infection
Here we report on a cohort of 63 COVID-19-convalescent individuals assessed at 1.3, 6.2 and 12 months after infection, 41% of whom also received mRNA vaccines. In the absence of vaccination antibody reactivity to the receptor binding domain (RBD) of SARS-CoV-2, neutralizing activity and the number of RBD-specific memory B cells remain relatively stable from 6 to 12 months. The data suggest that immunity in convalescent individuals will be very long lasting.
A long-term perspective on immunity to COVID
There is ongoing discussion about which aspects of the immune response to SARS-CoV-2 provide hallmarks of immunity. However, there is probably a consensus that the two main pillars of an antiviral response are immune cells called cytotoxic T cells, which can selectively eliminate infected cells, and neutralizing antibodies, a type of antibody that prevents a virus from infecting cells. A third pillar of an effective immune response would be the generation of T helper cells, which are specific for the virus and coordinate the immune reaction.