Is it necessary to take the COVID-19 vaccine, or can the host's immune system be sufficient to protect against the virus?

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I understand your query. To initiate infection in humans, there is something called the infective dose, which is nothing but the load or amount of microbe needed to initiate an infection. Examples are the infective load of Vibrio to cause diarrhea is high (about 10^6 to10^8 bacilli, since it is acid labile and has to pass to gastric acid), and an infective load of Salmonella to cause enteric fever is low (about 10^3 to 10^6 bacilli). However, pathogens like Shigella need 10 to 100 bacilli to initiate an infection leading to dysentery. When we come to a virus, it does not have an infective dose like bacteria. Very few viral particles are infectious due to intracellular survival and immune escape mechanisms. Viral load in viral infections is significant in assessing prognosis and complications, and the viral load depends upon the immunity of an individual. Certain individuals' cell-mediated and humoral immunity may be very good in suppressing viral replication leading to low viral load, fast viral clearance, low infectivity, and milder illness. On the other hand, individuals with low cell-mediated and humoral immunity and having conditions like uncontrolled diabetes and other factors may not be able to suppress viral replication leading to active replication of the virus along with low clearance of viral particles, which increases viral load and cell death. It can lead to a severe form of the disease and systemic inflammatory response syndrome (seen in COVID-19). In the case of COVID-19, the vaccine induces both humoral and cell-mediated immunity. Vaccinated individuals can still shed viral particles and infect other vaccinated or unvaccinated individuals, but the number will be less. The further replication and infectivity depend upon the factors I mentioned above, like even fewer viral particles will be able to produce an asymptomatic infection to severe infection, which depends upon the individual's immune status.

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I can understand your situation, but I suggest you encourage them to get the vaccines because all the vaccines available to date are really good.

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Welcome back to icliniq.com.

Less viral particles will take a long incubation period, whereas more viral particles will take a less incubation period to initiate infection. It is not that fewer particles will produce less severe infection, and more viral particles will produce a severe form of the disease. In both scenarios, the form of the disease depends on individual factors and immune status. Even a few viral particles spread extracellularly and are sufficient to involve the lower respiratory tract. More than lung involvement, we worry about our immune system's inflammatory response against these viruses causing the damage.

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Welcome back to icliniq.com.

I would like to inform you that COVID-19 is a viral pathogen.