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In this study involving household contacts of persons with laboratory-confirmed Covid-19, the risk of household transmission was 40 to 50% lower among household contacts of index patients who had received one dose of vaccine 21 days or more before testing positive than among contacts of unvaccinated index patients.

The B.1.617.2 (delta) Covid-19 variant has surged in India and spread worldwide. In a test-negative case–control study, the effectiveness of two doses of BNT162b2 was 94% against the B.1.1.7 (alpha) variant and 88% against delta; with the ChAdOx1 nCoV-19 vaccine, effectiveness was 74% and 67%, respectively. Protection after a single vaccine injection was low; two doses are needed.

A test-negative case–control study involving more than 6 million persons in England who received two doses of the ChAdOx1-S or BNT162b2 vaccine (interval, 3 to 12 weeks) showed high vaccine effectiveness against hospitalization and death from Covid-19 at 20 weeks or more after vaccination. Protection against infection waned. Waning was greater in older persons and those with underlying risk factors.

Each September in England, ≈1 million students relocate to study at universities. To determine COVID-19 cases and outbreaks among university students after their return to university during the COVID pandemic in September 2020, we identified students with COVID-19 (student case-patients) by reviewing contact tracing records identifying attendance at university and residence in student accommodations identified by matching case-patients' residential addresses with national property databases. We determined COVID-19 rates in towns/cities with and without a university campus. We identified 53,430 student case-patients during September 1-December 31, 2020, which accounted for 2.7% of all cases during this period. Student case-patients increased rapidly after the start of the term, driven initially by cases and outbreaks in student accommodations. Case rates among students 18-23 years of age doubled at the start of term in towns with universities. Our findings highlight the need for face-to-face and control measures to reduce virus transmission.

Background Growing numbers of people have been potentially exposed to avian influenza (AI), as the United Kingdom has managed the largest and most sustained series outbreaks in recent years. Antiviral medication is recommended for exposed individuals for chemoprophylaxis to reduce the severity of illness and the likelihood of secondary transmission. However, some individuals have been hesitant or declined antivirals. In this study, we aimed to identify the factors affecting the uptake of and adherence to antiviral medication. Methods We interviewed 14 individuals occupationally exposed to avian influenza and conducted focus groups with 15 public health professionals involved in advising and arranging antivirals. The data were analysed thematically based on COM-B factors (capability, opportunity, motivation). Results Although participants saw avian influenza as a severe disease, most did not consider themselves susceptible to it because they felt safe in personal protective equipment and knew that bird-to-human transmission was rare. The biggest barrier to uptake and adherence was experiencing side effects, especially if these disrupted day-to-day life or work. Participants who took antivirals followed medical advice in a novel situation, had health conditions or vulnerable family members they wanted to protect. As responding to an outbreak was exhausting, easy access to antivirals for those at most risk was considered important for improving uptake. Conclusions The factors affecting antiviral uptake were multifaceted. Public health interventions should prioritise those at most risk and address multiple components of behaviour, such as advising how to manage side effects, addressing concerns about long-term usage and providing convenient access to antivirals for those at most risk.

A single SARS-CoV-2 vaccine dose reduces onward transmission from case-patients. We assessed the potential effects of receiving 2 doses on household transmission for case-patients in England and their household contacts. We used stratified Cox regression models to calculate hazard ratios (HRs) for contacts becoming secondary case-patients, comparing contacts of 2-dose vaccinated and unvaccinated index case-patients. We controlled for age, sex, and vaccination status of case-patients and contacts, as well as region, household composition, and relative socioeconomic condition based on household location. During the Alpha-dominant period, HRs were 0.19 (0.13-0.28) for contacts of 2-dose BNT162b2-vaccinated case-patients and 0.54 (0.41-0.69) for contacts of 2-dose Ch4dOx1-vaccinated case-patients; during the Delta-dominant period, HRs were higher, 0.74 (0.72-0.76) for BNT162b2 and 1.06 (1.04-1.08) for Ch4dOx1. Reduction of onward transmission was lower for index case-patients who tested positive ≥2 months after the second dose of either vaccine.

Of the 58,186 coronavirus deaths among adults in England during March-December 2020, 77% occurred in hospitals, 93% were in patients >60 years, and 91% occurred within 28 days of positive specimen. Cumulative mortality rates were highest among persons of Black, Asian, other, or mixed ethnicities and in socioeconomically deprived areas.

Using laboratory data and a novel address matching methodology, we identified 734 cases of coronavirus disease in 88 prisons in England during March 16–October 12, 2020. An additional 412 cases were identified in prison staff and household members. We identified 84 prison outbreaks involving 86% of all prison-associated cases.

Background From 12th March 2020, individuals in England were advised to quarantine in their home if a household member tested positive for SARS-CoV-2. A mandatory isolation period of 10 days was introduced on 28th September 2020 and applied to all individuals with COVID-19. We assessed the frequency, timing, and characteristics of recovered COVID-19 cases requiring subsequent quarantine episodes due to household re-exposure. Methods In this case cohort study, all laboratory-confirmed COVID-19 cases notified in England (29th June to 28th December 2020) were analysed to identify consecutive household case(s). Multivariable logistic regression was used to determine associations between case characteristics and need to quarantine following recent infection (within 28 days of diagnosis). Results Among 1,651,550 cases resident in private dwellings and Houses of Multiple Occupancy (HMOs), 744,548 (45.1%) were the only case in their home and 56,179 (3.4%) were succeeded by further household cases diagnosed within 11–28 days of their diagnosis. Of 1,641,412 cases arising in private homes, the likelihood of further household cases was highest for Bangladeshi (aOR = 2.20, 95% CI = 2.10–2.31) and Pakistani (aOR = 2.15, 95% CI = 2.08–2.22) individuals compared to White British, as well as among young people (17-24y vs. 25-64y; aOR = 1.19, 95% CI = 1.16–1.22), men (vs. women; aOR = 1.06, 95% CI = 1.04–1.08), London residents (vs. Yorkshire and Humber; aOR = 1.57, 95% CI = 1.52–1.63) and areas of high deprivation (IMD 1 vs. 10; aOR = 1.13, 95% CI = 1.09–1.19). Conclusion Policies requiring quarantine on re-exposure differentially impact some of the most disadvantaged populations. Quarantine exemption for recently recovered individuals could mitigate the socioeconomic impact of responses to COVID-19 or similar infectious disease outbreaks.

Background. Infants with pertussis infection are at risk of severe clinical illness and death. Several countries, including the United Kingdom, have introduced maternal pertussis vaccination during pregnancy to protect infants from infection following national increases in pertussis notifications. The objective of this study was to estimate the effectiveness of maternal pertussis vaccination in protecting infants against laboratory-confirmed pertussis infection. Methods. A case-control study was undertaken in England and Wales between October 2012 and July 2013. Cases were infants aged <8 weeks at onset with pertussis infection tested by real-time polymerase chain reaction or culture. Family doctors of each case were asked to identify healthy infants born consecutively after the case in each practice, to act as controls. Fifty-eight cases and 55 controls were included in this study. Odds ratios (ORs) were calculated for the association between maternal vaccination and infant pertussis infection. The vaccine effectiveness (VE) was calculated as 1 – OR. This was adjusted for sex, geographical region, and birth period. Results. Mothers of 10 cases (17%) and 39 controls (71%) received pertussis vaccine in pregnancy. This gave an unadjusted VE of 91% (95% confidence interval [CI], 77%–97%). Adjusted VE was 93% (95% CI, 81%–97%). Conclusions. Maternal pertussis vaccination is effective in preventing pertussis infection in infants aged <8 weeks and may be considered in other countries experiencing high levels of pertussis notifications.