The protective effect of previous COVID-19 infection in a high-prevalence hospital setting.

OBJECTIVE: To assess the protective effect of previous COVID-19 infection for healthcare workers in a high-prevalence setting. METHOD: The COVID-19 antibody and PCR results of 538 healthcare workers on wards with COVID-19 outbreaks from 1 March 2020 to 31 July 2020 were evaluated. Infection rates of the 'previously infected' and 'no evidence of previous infection' groups were compared during second-wave outbreaks between 29 September 2020 and 20 November 2020. RESULTS: One out of 115 individuals previously infected developed infection compared with 104 out of 423 individuals with no evidence of previous infection. Attack rates in staff previously infected was reduced significantly from 24.59% to 0.87% (odds ratio 0.027, 95% CI 0.004-0.195, p<0.001) when compared to the 'no evidence of previous infection' group with the same exposure risk. CONCLUSION: Prior SARS-CoV-2 infection offers significant protection against reinfection and this protection lasts 4 months for the majority of individuals.

The impact of false positive COVID-19 results in an area of low prevalence.

False negative results in COVID-19 testing are well recognised and frequently discussed. False positive results, while less common and less frequently discussed, still have several adverse implications, including potential exposure of a non-infected person to the virus in a cohorted area. Although false positive results are proportionally greater in low prevalence settings, the consequences are significant at all times and potentially of greater significance in high-prevalence settings. We evaluated COVID-19 results in one area during a period of low prevalence. The consequences of these results are discussed and implications for these results in both high and low prevalence settings are considered. We also provide recommendations to minimise the risk and impact of false-positive results.

The clinical sensitivity of a single SARS-CoV-2 upper respiratory tract RT-PCR test for diagnosing COVID-19 using convalescent antibody as a comparator.

The clinical false negative rate of reverse transcriptase polymerase chain reaction (RT-PCR) testing for SARS-CoV-2 on a single upper respiratory tract sample was calculated using convalescent antibody testing as a comparator. The sensitivity in symptomatic individuals was 86.2% (25/29). Of the missed cases, one (3.5%) was detected by repeat RT-PCR, one by CT thorax and two (7.1%) by convalescent antibody. The clinical false negative rate of a single RT-PCR on an upper respiratory tract sample of 14% in symptomatic patients is reassuring when compared to early reports. This report supports a strategy of combining repeat swabbing, use of acute and convalescent antibody testing and CT thorax for COVID-19 diagnosis.

Growing up with perinatal HIV: changes in clinical outcomes before and after transfer to adult care in the UK.

INTRODUCTION: With improved survival, adolescents with perinatal HIV (PHIV) are transitioning from paediatric to adult care, but there are few published data on clinical outcomes post-transfer. Using linked data from patients in the national UK/Ireland paediatric cohort (CHIPS) and an adult UK cohort of outpatient clinics (UK CHIC), we describe mortality and changes in immunological status post-transfer. METHODS: Participants in CHIPS aged ≥13 years by the end of 2013 were linked to the UK CHIC database. Mixed effects models explored changes in CD4 count before and after transfer, including interactions between time and variables where interaction p < 0.05. RESULTS: Of 1,215 paediatric participants aged ≥13 years, 271 (22%) had linked data in UK CHIC. One hundred and forty-six (53%) were female, median age at last visit in paediatric care was 17 [interquartile range, IQR 16,18] years, median duration in paediatric care was 11.8 [6.6,15.5] years, and in adult care was 2.9 [1.5,5.9] years. At last visit in paediatric care, 74% (n = 200) were on ART, increasing to 84% (n = 228, p = 0.001) at last visit in adult care. In the 12 months before leaving paediatric care, 92 (47%) had two consecutive viral loads >400 copies/mL or one viral load >10,000 copies/mL, and likewise 102 (52%) in the 12 months post-transfer (p = 0.79). Seven (3%) people died in adult care. In multivariable analysis, CD4 declined as patients approached transition with a greater decline in those with higher nadir CD4 count (mean rates of decline of 3, 13, 15, 30 cells/mm3 per year for those with nadir CD4 < 100, 100-199, 200-299 and ≥300 cells/mm3, respectively). Post-transition, CD4 continued to decline in some groups (e.g. black males, -20 (-34, -5) cells/mm3 per year post transition, p = 0.007)) while it improved in others. Overall CD4 was higher with later year of birth (14 (7, 21) cells/mm3 per later year). There was no effect of age at transfer or changing hospital at transfer on CD4. CONCLUSIONS: Our findings suggest that CD4 in adolescents with perinatal HIV in the UK was declining in the period before transition to adult care, and there was some reversal in this trend post-transfer in some groups. Across the transition period, CD4 was higher in those with later birth years, suggesting improvements in clinical care and/or transition planning over time.