Less effective vaccines still protect against severe disease
SARS-CoV-2 escaped natural immunity, raising questions about vaccines and therapies
A striking impact on vaccine efficacy against variant B.1.351 has been observed. The efficacy of Novavax vaccine NVX-CoV2373 dropped from 96% to 48% (ref. 13); the efficacy of the Johnson & Johnson vaccine JNJ-78436735 decreased from 85% to 57% (ref. 14); and the efficacy of the Oxford–AstraZeneca vaccine ChAdOx1 dropped from 62% to 10% (ref. 15). Those drops were matched by a 7- to 12 -fold decrease in the titer of vaccine-induced neutralizing antibodies against the B.1.351 variant reported for the mRNA-based vaccines, whereas no effect on the neutralization titer was observed for the B.1.1.7 variant. Fortunately, despite the loss of efficacy of all vaccines analyzed, NVX-CoV2373 and JNJ-78436735 showed almost complete protection against severe disease caused by the B.1.351 variant.
Assessment of effectiveness of optimum physical distancing phenomena for COVID-19
This paper aims to provide safe distance recommendations among individuals and minimize the spread of COVID-19. In cases where there were no wind conditions, the breathing and coughing simulations display 1–2 m physical distancing to be effective. However, when sneezing was introduced, the physical distancing recommendation of 2 m was deemed not effective; instead, a distance of 2.8 m and greater was found to be more effective in reducing the exposure to respiratory droplets. Coughing caused a change from the previous recommendation of 2 m to a distance of 4.5 m or greater. Sneezing in the presence of a gentle breeze was deemed to be the most impactful, with a recommendation for physical distancing of 5.8 m or more. It was determined that face coverings can potentially provide protection to an uninfected person in static air conditions.
Natural ventilation strategy and related issues to prevent coronavirus disease 2019 (COVID-19) airborne transmission in a school building
This study uses field measurements to analyze the natural ventilation performance in a school building according to the window opening rates, positions, and weather conditions. Under cross-ventilation conditions, the average ventilation rates were measured at 6.51 h−1 for 15% window opening, and 11.20 h−1 for 30% window opening. For single-sided ventilation, the ventilation rates were reduced to about 30% of the values from the cross-ventilation cases. The infection probability is less than 1% in all cases when a mask is worn and more than 15% of the windows are open with cross-ventilation. With single-sided ventilation, if the exposure time is less than 1 h, the infection probability can be kept less than 1% with a mask. However, the infection probability exceeds 1% in all cases where exposure time is greater than 2 h, regardless of whether or not a mask is worn.
Mitigation of Airborne Contaminant Spread through Simple Interventions in an Occupied Single-Family Home
The intent in existing homes is to find a practical means to mitigate exposure to airborne contaminants. The best containment strategy was achieved through continuously operating the bathroom exhaust fan while keeping the windows closed in the isolation zone (IZ) (configuration 2). Interventions using open windows were found to be less reliable, due to variability in wind speed and direction, resulting in an unpredictable and sometimes detrimental pressure differential in the IZ with reference to main zone. Our findings strongly suggest a simple IZ exhaust ventilation strategy has the potential for mitigating the risk from the airborne spread of contaminants, such as SARS-CoV-2.
The potential for vaccination-induced herd immunity against the SARS-CoV-2 B.1.1.7 variant
The feasibility of attaining vaccination-induced herd immunity depends on (i) vaccine effectiveness in reducing transmission, (ii) the transmissibility of the target pathogen and (iii) the vaccine coverage that is achievable in a population. Comparing this theoretical HIT with estimated values of R0 and vaccine effectiveness for a range of vaccine-preventable diseases (Figure 1), we see that for infections caused by viruses with little antigenic variation, vaccine effectiveness is sufficiently high to control transmission if high vaccine coverage is achieved. This is why, in many countries, childhood immunisation programmes have led to elimination of viruses with little antigenic variation and long-lasting sterilizing immunity, such as measles and rubella viruses.