DR NIGHAT NAZIRÂ
1. Increased contagious window
An individual is infectious while the virus is replicating in the upper respiratory tract. A variant of concern could increase in the length of time that the virus replicates, thereby increasing the contiguous window. The longer someone is contagious, the more chances they have to pass on the infection to someone else.
2. Increased viral shedding
SARS-COV-2 passes from person to person via droplets and aerosols that are `shed` when someone breaths, speaks, coughs, or sneezes. A variant of concern could increase the amount of virus that someone sheds, increasing the likelihood of passing on the infection.
3. Increased Environmental Stability
Fomite transmission occurs when someone gets infected with SARSCOV-2 after touching the surface or object containment with the virus. A variant of concern may survive longer on surfaces.Â Importantly increased environmental stability may also include prolonged survival in the aerosols and droplets.
4. Increased binding to host receptors
SARS-COV-2 infects us by binding to a receptor, called the ACE2 Receptor, on cells in a respiratory tract. A variant of concern might bind to ACE2 better, increasing the ability of virus to infect ourselves.
WHO (World Health Organization) decided on 31st -May to name the variants Alpha, Beta, Gamma and Delta in order to avoid discrimination between the countries.
1. ALPHA Variant (B.1.1.7): detected on September 2020 located first in U.K was named as U.K variant. It spreads more easily and could increase death rate.
2. BETA Variant (B.1.351): detected on August 2020 located first in South Africa was named as South African Variant. It spreads more easily and some vaccines may be less effective against it.
3. GAMMA Variant (P.1): was detected on December 2020 located first in Brazil and was named as Brazilian variant. It spreads more easily and some vaccines may be less effective against it.
4.Â DELTA Variant (B.126.96.36.199): was detected on October 2020 located first in India was named as Indian variant. The COVID19 Delta variant is more transmissible than the Alpha variant or original coronavirus, which requires more people to be vaccinate in order to have protection from herd immunity.
R0 number also called as R Naught of COVID19 Variants, varies from variant to variantÂ
R0 less than 1 means transmission would die down and R0 more than 1 would mean it would be sustained , for Ancestral COVID19 (SARS CoV2) R0 is three (3) which means that three new cases are being infected with the virus by the index case.
R0 for alpha variant is 4-5 means each case of alpha variant produces 4-5 new cases and for delta variant it is 5-8.
Among other communicable diseases like Mumps R0 is 12 and it is highest for Measles which is 8
The more contagious, the higher the RO number
Vaccine Efficacy and VariantsÂ
Good news is that all variants are susceptible to current vaccines.
Take Home Message
Follow covid appropriate behaviors (CAB) that is masking, physical distancing and frequent hand wash and go for vaccination once you are eligible.
(Author is Nodal officer (SNO), Climate Change and Human Health (CCHH) Directorate of Health Services, Kashmir, India. E mail: email@example.com)