COVID-19 is a disease caused by the novel Coronavirus, which was identified as the source of a cluster of cases of pneumonia in Wuhan, China. The infection is named coronavirus 2 (SARS-CoV-2) due to its genetic relation and similarities to the coronavirus responsible for the SARS outbreak of 2003. The COVID-19 spread rapidly worldwide and resulted in a global pandemic. The ongoing pandemic has resulted in over 270 million reported cases of contraction and over 5 million deaths.
Over time, the COVID-19 virus has evolved, leading to mutations in the virus' genome. These mutations have resulted in the emergence of several variants of the COVID-19. These variants are dangerous due to increased transmissibility, greater risk of severe disease, reduction in neutralisation by antibodies generated during previous infection or vaccination, or reduced efficacy of treatments or vaccines.
| WHO Label | First Detected | When | Known Characteristics |
|---|---|---|---|
| Alpha | United Kingdom | Late 2020 |
50% increased transmission. Potential increased severity based on hospitalizations and case fatality rates. |
| Beta | South Africa | Late 2020 |
50% increased transmission. |
| Gamma | Japan/ Brazil |
December 2020 |
Potential for increased transmissibility. |
| Delta | India | December 2020 |
Increased transmissibility compared with Alpha. Potential increased severity based on associated hospitalisation rate. Potential modest/moderate reduction in vaccine effectiveness against symptomatic COVID-19 without significant impact on vaccine effectiveness against severe disease. |
| Omicron | Botswana/ South Africa |
November 2021 |
Clinical implications are not yet known. |
Booster vaccine doses are administered to vaccinated individuals that have completed a primary vaccination series (currently one or two doses of COVID-19 vaccine, depending on the product). Boosters are administered to ensure that the individual’s immunity and clinical protection do not fall below a threshold deemed insufficient to protect individuals from contracting the virus.
The rationale for booster vaccination should be guided by evidence on vaccine effectiveness, particularly against severe COVID cases in the general and high-risk populations or due to a circulating variant of concern. Hitherto, evidence remains limited and inconclusive on any widespread need for booster doses following a primary vaccination series. In the United States, the Food and Drug Administration (FDA) and CDC has authorised a booster dose for all individuals 16 years or older, regardless of the type of vaccine received.
With the emergence of the Omicron variant, Pakistan's National Command and Operation Centre (NCOC) has expanded the COVID vaccination drive. As a result, booster doses, which were previously only available for international travellers with mandatory vaccination requirements, are now free-of-cost to healthcare workers, citizens over the age of 50, and the immunocompromised.
While promising new treatments including antiviral drugs are emerging, preventive measures to reduce the risk of transmissions such as vaccination, mask-wearing in public, hand washing, social distancing, respiratory hygiene, and avoiding crowds and close contact with ill individuals, continue to be the primary means of protection against the deadly COVID-19 and its variants.
Contributed by:
Dr.Sikandar S. Imran, MD
Acting Medical Director / Associate Director Clinical Services
*References are available on demand
