Changes in symptomatology, re-infection and transmissibility associated with SARS-CoV-2 variant B.1.1.7: an ecological study

Abstract

The new SARS-CoV-2 variant B.1.1.7 was identified in December 2020 in the South-East of England, and rapidly increased in frequency and geographic spread. While there is some evidence for increased transmissibility of this variant, it is not known if the new variant presents with variation in symptoms or disease course, or if previously infected individuals may become reinfected with the new variant. Using longitudinal symptom and test reports of 36,920 users of the Covid Symptom Study app testing positive for COVID-19 between 28 September and 27 December 2020, we examined the association between the regional proportion of B.1.1.7 and reported symptoms, disease course, rates of reinfection, and transmissibility. We found no evidence for changes in reported symptoms, disease severity and disease duration associated with B.1.1.7. We found a likely reinfection rate of around 0.7% (95% CI 0.6-0.8), but no evidence that this was higher compared to older strains. We found an increase in R(t) by a factor of 1.35 (95% CI 1.02-1.69). Despite this, we found that regional and national lockdowns have reduced R(t) below 1 in regions with very high proportions of B.1.1.7.

Immune response to SARS-CoV-2 variants of concern in vaccinated individuals

“…In response, the scientific community has made unprecedented progress, resulting in the generation of multiple vaccines, using a variety of different approaches 8,15,16 , such as the Pfizer BNT-162b2 vaccine, which encodes a full-length trimerized spike protein 17 . In parallel, SARS-CoV-2 is continually evolving which might impact its infectivity 2 , transmission 3,18,19 and viral immune evasion 20,21 . To date, advanced genomic approaches have identified thousands of variants of SARS-CoV-2 with multiple RBD mutations circulating due to natural selection 4,22 .…”

“… Abstract The SARS-CoV-2 pandemic virus is consistently evolving with mutations within the receptor binding domain (RBD) 1 being of particular concern 2-4 . To date, there is little research into protection offered following vaccination or infection against RBD mutants in emerging variants of concern (UK 3 , South African 5 , Mink 6 and Southern California 7 ). To investigate this, serum and saliva samples were obtained from groups of vaccinated (Pfizer BNT-162b2 8 ), infected and uninfected individuals.…”

Controlling the pandemic during the SARS-CoV-2 vaccination rollout: a modeling study

“…variant in Portugal. The situation in mid-march 2021 is then described by the average number of daily contacts of 4.2, R e of 0.67 and the circulating variant that is 50% more transmissible [5][6][7] than the original variant that was dominant in Portugal until December 2020. Starting from this situation, we generated scenarios for relaxation of control measures as follows (Figure 6): Scenario 1) lifting all measures so that contact rates in the population return to the pre-pandemic level (average rate of 12.6 contacts/day); Scenario 2) partial lifting of measures that increases contact rates to the level of September-October 2020 (7.6 contacts/day); Scenario 3) partial lifting of measures that increases contact rates to the level of June-August 2020 (5.9 contacts/day).…”

“…The rapid spread of B.1.1.7 variant, that is estimated to be about 50% more transmissible based on the data from England [5][6][7], fueled the third wave of hospitalizations in Portugal. The increasing dominance of this variant was modelled empirically as a gradual increase in the probably of transmission per contact by 50% as follows [1 + 0.5/(1 + e −K0(t−t data ) )], where and K 0 were estimated based on the data until 15 January 2021 (Figure S2) and t data is the last date in the hospital admission data (15 January 2021).…”

“…Despite elaborate national vaccination schedules, it remains unclear when and which control measures can be relaxed and at which point the control of the pandemic will be achieved as the vaccination is rolled out in 2021. The understanding of how relaxation policies might affect the transmission of SARS-CoV-2 is further hampered by the emergence of novel variants [3,4] that have a selective advantage, such as increased transmissibility [5][6][7] or the ability to reduce rapid neutralisation by the host [8]. For example, the current restrictions in Europe [9] are in part caused by a more transmissible [5][6][7] and potentially more pathogenic [10,11] B.1.1.7 variant that originated in the UK and is quickly gaining dominance in other countries including Portugal [12,13].…”