Within a month of it being labelled as variant of concern by the World Health Organization, the Omicron variant is spreading rapidly across the world. It has become the dominant variant in the US and Europe. As per latest data, it appears that it has already peaked in South Africa with new cases and hospitalizations showing a declining trend. Fortunately, the number of hospitalizations and deaths are far less during the present wave in South Africa than the previous ones, giving a hope that the Omicron variant is less lethal. Whether this can be extrapolated to other countries is being keenly watched as population characteristics can differ from one country to another.
While the mean age of the population in South Africa is lower when compared to western nations, the vaccination rate is much lower. However, sero-prevalence rate is far higher due to prior natural infections. Another variable that influences the clinical behavior of the COVID-19 illness is the immune response mounted by people. The last variable is the behavior of the virus itself. In laboratory studies, it is being noticed that Omicron virus replicates less in lower airways and lung parenchyma compared to upper airways tissue. However, in these studies the impact of immune response on tissue injury is not adjusted for. Given the above facts, it is too early to hope that Omicron is less lethal than Delta.
Even if it is less lethal, the surge of people needing hospitalizations, oxygen therapy and ventilator therapy may surpass the previous waves due to the speed at which Omicron is spreading. The best recourse to slow the spread and blunt the surge is to institute basic containment measures of face mask, hand wash, and social distancing. Mandated restrictions on gatherings that have the potential to be super-spreader events will help in slowing the spread. Not serving meals on flights is an example of a simple measure.
Though current vaccines may be far less effective against the Omicron variant, they still provide protection against severe illness and deaths at least up to three months after the second dose or booster dose. However, the effectiveness may vary according to the type of vaccine. In laboratory studies involving neutralizing antibody levels against Omicron variant, mRNA-based vaccines had the highest antibody levels followed by adenovirus-based vaccines, finally followed by inactivated virus vaccines. Hence, eligible people who are not yet vaccinated should get vaccinated. Elderly people with comorbidities who have received two doses may consider taking a booster if the last dose was taken more than three months ago. The Government of India recently used guidelines according to which Covaxin will be administered to children aged 15-18 starting January 3, 2021. The central government also released guidelines on ‘precaution doses’ for frontline workers and people above the age of 60 years with co-morbidities, to be started from January 10 onwards.
There is an ongoing debate on the origins of the Omicron variant. One of the prevalent hypotheses is that the variant arose in an immune-compromised patient given the wide prevalence of HIV in Africa. Other equally strong hypothesis gaining ground is that the variant might have jumped from an animal reservoir. It really does not matter how the variant arose. What matters is that the virus will undergo mutations as long as it has a host to multiply. It may be a human host or an animal host. The only way to lessen the risk of future variants is to prevent its transmission. The easy way to prevent transmission is adopting COVID appropriate behavior of face masking, hand washing, and social distancing.
In summary, the following facts may be used in how we prepare ourselves against the inevitable third wave:
- Omicron is far more transmissible than Delta
- Omicron is causing breakthrough infections in vaccinated people and reinfections in people with prior infection
- Prior infections and vaccines may not prevent infection with Omicron. However, they seem to reduce the chances of developing severe illness and death
- Cautious optimism should be exercised in interpreting lower hospitalizations and deaths in South Africa
- Covid appropriate behavior is still the best bet to prevent surges and avoid lockdowns
- Vaccines for unvaccinated and boosters for high risk people may be a preferred choice
- We should continue to be watchful about new variants
Dr Krishna Reddy Nallamalla
Regional Director, ACCESS Health International
Photo Credits: Down to Earth