ABSTRACT
Background. Understanding how COVID-19 vaccination affects transmission of SARS-CoV-2 within households may affect policy and healthcare decisions. We hypothesized that vaccination reduces transmission and viral load in vaccinated household members. Methods. We prospectively enrolled participants during March 2020 - October 2021. Index cases (IC) were eligible if they tested positive for SARS-CoV-2 within the previous 10 days and did not have household contacts (HC) who had tested positive or had symptoms of COVID-19. Participants self-collected anterior nares swabs daily for SARS-CoV-2 RT-PCR for at least 21 days, or once every member of the household had 7 consecutive negative tests. Baseline data included demographics and self-reported vaccination status. Complete COVID-19 vaccination was defined as receiving 2 doses of Moderna/Pfizer or 1 dose of Johnson & Johnson vaccine, and incomplete vaccination as receiving 1 dose of Moderna/Pfizer vaccine. Household transmission was analyzed via STATA 14.2 using logistic regression with robust standard error clustered by household, and SARS-CoV-2 cycle threshold was graphed by day of study enrollment using lowess smoothing. Results. There were 60 households with positive ICs and 103 HCs for a total of 163 participants. ICs had median age 41.5 years (range 1-86) with 9 (18.0%) < 18 years. HCs had median age 34 years (range 0-87) with 32 (31.1%) HCs < 18 years. Overall, 33 (20.2%) participants received at least one COVID-19 vaccine dose. A total of 50 households had at least one HC (median 2, max 7). Transmission of SARS-CoV-2 occurred in 45 HCs (43.7%). Odds of SARS-CoV-2 transmission was lower in HCs who were vaccinated prior to study enrollment, though this finding was not statistically significant (Table 1). There were 507 positive SARS-CoV-2 tests collected among 74 participants (Figure 1). Completely vaccinated: Received primary COVID-19 vaccination series (2 doses Pfizer or Moderna vaccine, or 1 dose Johnson & Johnson vaccine) prior to enrollment Conclusion. Vaccination of HCs may be protective against household SARS-CoV-2 transmission. However, analyses were limited due to low numbers of vaccinated study participants. Study enrollment is ongoing, and future analyses will include transmission during the 2022 Omicron surge, and daily symptom data which has been collected.
ABSTRACT
Background: The mechanism of bone loss in antiretroviral-treated HIV-positive patients is poorly understood. Plasma bone turnover markers(BTMs) suggest uncoupling of bone resorption and formation by a treatment effect on bone cells. Switching away from TDF to TAF-containing regimens has been associated with bone mineral density(BMD) gains measured by dual-energy X-ray absorptiometry (DXA). One explanation is reversal of ongoing subclinical bone loss in the TDF to TAF switchers. Quantitative imaging with 18F-PET/CT allows assessment of regional bone formation at specific skeletal sites and can help differentiate if BMD changes are associated with increased bone formation or reduced bone loss. Methods: PETRAM, an open-label, randomised study conducted at a single UK site, enrolled non-osteoporotic virologically suppressed HIV-positive males, on >24 weeks rilpivirine/emtricitabine/TDF (RPV/FTC/TDF). They were randomised 1:1 to remain on RPV/FTC/TDF or switch to RPV/FTC/TAF. The protocol specified scanning by DXA (to measure BMD) and 18F-PET/CT at several regions of interest-with primary focus on the lumbar spine (LS) and total hip (TH)-at baseline, 24 weeks, and 48 weeks. However, the timing of scans was disrupted, and in some cases considerably delayed, by COVID-19. The primary analysis was therefore based on change between the baseline and final scans, adjusting for the interval between them. Regions of interest were drawn on the PET/CT images and the standardised uptake value (SUV) measured. A sample of 30 (15 per arm) was estimated to provide 90% power to detect a difference in change of 25% in SUV between the randomised groups. Results: 32 males, median age 51 years, 76% White ethnicity, median duration RPV/FTC/TDF of 49 months, BMI 25.5 kg/m2 were enrolled;27(16 TAF:11 TDF) were included in the final analysis. The interval between baseline and final scans ranged between 23-103 weeks (median 55 weeks). There was no significant difference in change in SUV(18F-PET/CT) at the LS or TH between the TAF and TDF arms (Table);there was a trend towards improved LS BMD, but not TH BMD, in the TAF arm. Conclusion: As measured by 18F-PET/CT, regional bone formation at the hip or LS in patients replacing TDF with TAF in their ART combination did not differ, and contrary to our hypothesis, switching to TAF vs. remaining on TDF over 23-103 weeks did not change BMD or SUV at these key skeletal sites. The improved LS BMD in those switching to TAF is consistent with findings from other TAF-switch studies.