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COVID-19 and the variants

In December 31st 2019, first case of coronavirus disease 2019 (COVID-19) was reported to World Health Organization (WHO). On March 11th 2020, WHO declared COVID-19 a pandemic and US government declared COVID-19 a national emergency after 2 days. On December 31st, 2019, the first coronavirus disease 2019 (COVID-19) case was reported to the World Health Organization (WHO). On March 11th, 2020, WHO declared COVID-19 a pandemic, and the U.S. government declared COVID-19 a national emergency after 2 days. The COVID-19 is caused by a novel coronavirus, SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), which emerged in December 2019 from Wuhan, China. COVID-19 might cause respiratory symptoms, such as fever, cough, shortness of breath, fatigue, body aches, and headaches. Some people might lose their taste or smell. Additionally, it might induce more severe diseases like SARS (severe acute respiratory syndrome) and MERS (Middle East respiratory syndrome). Its transmission could be spread in three ways: First, an infected person could exhale tiny droplets and particles containing the virus. If another person is nearby within 6 feet, this healthy person might get the virus from these particles. Second, these small droplets and particles with the virus might land on the eyes, nose, or mouth through an infected person’s coughs or sneezes. Third, if your hand has a virus on it, and you use it to touch eyes, nose, or mouth, then you might get an infection. To protect ourselves and our family, wearing a medical-grade mask is an important step because the surgical mask constitutes an electrospinning fibers layer with static electricity to capture the virus. Moreover, keeping 6 feet distance from others might also lower the risk of getting an infection. The last way to protect ourselves from COVID-19 is vaccine administration. Up to date, there are three FDA-approved vaccines in the U.S., Moderna mRNA-based vaccine, Pfizer mRNA-based vaccine, and Johnson & Johnson adenovirus-based vaccine. These vaccines could effectively stimulate the immune response to allow our bodies to produce antibodies to fight coronavirus.

Interestingly, the name coronavirus is not named from Corona beers. It actually means crown structure because coronavirus has spike proteins on its capsid, and it looks like a crown. These spike proteins play an essential role not only in virus transmission but also in vaccine development. In the transmission process, the spike protein would bind to a typical protein receptor on the cell surface of human throat and lung cells, called ACE2 receptor (Figure 1), and fuse with human cells to transfect it. On the other hand, scientists have developed a COVID vaccine to produce antibodies to target the spike proteins. While the COVID virus has been widely spread, more and more variants appear with mutations in spike protein. For example, the Alpha variant of COVID-19 has ten mutations in the sequence of spike protein which could help the virus to bind to the human cell easier. Up to date, there are five significant variants that exit after pandemic: Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), Delta (B.1.617.2), and Omicron (B.1.1.529). The Alpha variant was first found in the United Kingdom in September 2020. The Beta variant was discovered in South Africa in May 2020. The Gamma variant was documented in Brazil in November 2020. In 2021, Delta, the primary variant, was identified in India in October 2020. In 2022, the Delta variant was replaced by a higher infectious version, the Omicron variant, which occurred in multiple countries from November in 2021. At least 36 mutations were found in the omicron variant in the spike protein. These mutations might be the reason that omicron has become the most contagious variant in the world. Although the transmission rate of the omicron variant is higher than other variants, the toxicity/ damage to the lung is lower. In recent animal studies, scientists have discovered that the infection sites of the omicron variant would result mainly in the upper respiratory tract but less in lower respiratory and lung damages. This might imply that the pandemic would end soon because the trend of viral mutation would be a higher transmission rate but lower toxicity to humans.

Figure 1, The structure of coronavirus is constituted of single strand of RNA and envelop with spike protein which could bind to ACE2 receptor on human cells. Adapted from an image by Davian Ho for the Innovative Genomics Institute.

In sum, although the omicron variant might affect our daily lives, we could protect ourselves and our family by three methods described above, mask, 6 feet distance, and vaccine. If you have not received the COVID vaccine, please remember to get it, including a booster shot, to get full protection. With the oral pill from Pfizer (PAXLOVID) and Merck (molnupiravir), I believe the pandemic would end soon, and everyone could have a normal life again.

Reference:

  1. U.S. Centers for Disease Control and Prevention https://www.cdc.gov
  2. Megan Scudellari, Nature 595, 640-644 (2021)
  3. Leung, N.H.L. Transmissibility and transmission of respiratory viruses. Nat Rev Microbiol19, 528–545 (2021). https://doi.org/10.1038/s41579-021-00535-6

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Jason(Yen-Chun) Lu, All right reserved.