Being a doctor, a COVID frontline worker and clinical researcher, let me give you a medical point of view.
Vaccines are important; they help prep your immune system for an impending infection. This is done so by introducing the specific organism in a live weakened form (called Live attenuated, Eg: Varicella vaccine for Chicken Pox or MMR vaccine for Measles, Mumps, Rubella), dead form (called inactivated, Eg: for Hepatitis A or Rabies) or in form of the toxin produced by the organism (does not contain the organism itself, Eg: for Tetanus)
Vaccines work by developing antibodies against the said organism causing the disease which gets stored in the long term (Specifically IgG antibodies) and are called for by the body when the actual organism enters the body in the future to cause an infection. Now that being said, this
"Long Term" varies from vaccine to vaccine and is different for different disease.
The closest example to COVID19 (belonging to the Coronaviridae family) is another organism belonging to the Orthomyxoviridae family, i.e. Influenza virus (commonly referred to as the "Flu").
Ideally, the Flu vaccine has to be taken Annually and sometimes Bi-Annually, more specifically, every Flu season. India has two Flu Seasons, major peak in January to March and minor peak in August to October, making the Flu vaccine have an average life in your body of around 6 months-1 year. However, the majority of the population does not take the Flu vaccine as mentioned and DOES NOT need to take it. The people who actually need to take it are those belonging to high-risk groups such as patients who are immunocompromised (Eg: Geriatric age group, those who are on immunosuppressive therapy for reasons such as post-transplant or those suffering from autoimmune disease, etc.) or those who are hyper exposed to the virus (Eg: health care workers)
Now from the above logic, when the COVID vaccine comes, don't think that you can take it once and be immune for life. Just like every other vaccine, the antibodies within you will only last for that long
(maybe 6 months, 1 year, 5 years? We would know only after the vaccine is made) after which if the body does not see the organism again within it (either by infection or vaccination), it will slowly start diminishing the antibody levels to point where they are still present but in negligible amounts. The important point here is, after that period is over,
you can get reinfected again. However, since you still have negligible antibodies in you, your body will have the capacity to make new ones to fight off the disease faster compared to the first time you got infected where you had ZERO antibodies to begin with. CONCLUSION: COVID19 is new. We all are getting infected for the first time, hence the big commotion, eventually even though the vaccine comes, we still might get infected someday. We won't become as sick, we'll mostly survive (unless you fall in the high-risk category which puts you at a higher risk). Should we take the vaccine the first time? Probably yes, to prime our immune system to develop our first set of antibodies. Should we keep taking it every season? Eventually not, cause just like the Flu, over time your body will always store some negligible antibodies at your baseline, even when not infected/vaccinated, which will keep you relatively safe (not from getting infected over the long term for which you HAVE TO get vaccinated seasonally, but mostly from an outcome of poor prognosis). And with that soon the pandemic will end (as seen historically), and a bright future will emerge.
Please note, vaccines take time to develop and can only be safe after sufficient long term clinical testing trials. The fastest we made a vaccine till date, was the one for Ebola, and that took
5 years! This time, we may break the previous record and make it possible in 18 months; however, there will always be hurdles of availability. India has a population of 1.3 Billion people, meaning we'll need 1.3 Billion vials of vaccine. In my opinion, take all the vaccine news hyped out there with a pinch of salt. Expect the vaccine to be injected within you no sooner than mid of next year.