The importance of developing a vaccine for COVID-19 is an understatement. It is seen as the golden ticket for us all to return to our normal lives.
The ideal vaccine protects against infection, prevents its spread, and does so safely.
The reality is none of this is easily achieved.
There are over 150 COVID-19 vaccines in development.
Almost all governments worldwide are using vaccines for dealing with the coronavirus pandemic.
This is based on the idea that one of these vaccine candidates will eventually provide widespread protection against the virus.
There is no guarantee that this will happen.
Even in the most optimistic cases, we can not yet be sure that any vaccine will permanently prevent people from catching COVID-19 and enable the disease to be gradually eradicated or at least contained to limited outbreaks.
Vaccines may just reduce the severity of symptoms or provide temporary protection.
Scientists have worked on coronavirus vaccines before, so they are not starting from scratch.
Two coronaviruses have caused lethal outbreaks before, namely SARS and MERS, and vaccine research went ahead for both.
None have been licensed, partly because Sars faded out and Mers is regional to the Middle East.
The lessons learned will help scientists create a vaccine for Sars-CoV-2, but there is still an awful lot to learn about the virus.
The genetic stability of the virus matters, some viruses like influenza mutates so rapidly that vaccine developers have to release new formulations each year. The constant evolution of HIV is a huge reason we have no vaccine for the disease.
Scientists must study and continue analyzing COVID-19 in order to understand how it will mutate.
Some people have argued that when enough of the population has caught COVID-19 and produced an immune response to it, we will have reached "herd immunity" and the virus will no longer be able to spread.
Herd immunity is what enables us to eliminate diseases using vaccines. The percentage of a population who need to be vaccinated to reach herd immunity is calculated using the basic reproductive rate (R0).
The higher the R0 number, the more people need to become immune through vaccination to halt the spread.
Herd immunity can not be achieved by natural infection.
Numerous diseases have been eliminated in many countries thanks to herd immunity produced by vaccination programmes. But herd immunity is not something that can be achieved by natural infection.
This is why vaccines are necessary.
In the rush to develop a vaccine, safety must remain a priority.
Unlike experimental drugs for people who are severely ill, the vaccine will be given to potentially billions of generally healthy people.
This means scientists will have to check extremely carefully for signs of dangerous side-effects.
Side-effects like “antibody-induced enhancement” where the antibodies produced by a vaccine actually make future infections worse.
We also need to understand the fact that some people cannot have the vaccine when it is available, for medical reasons and some people will refuse it due to personal beliefs and opinions.
Given that 1.13 million people have died from COVID-19 worldwide so far and many people are reporting long-term effects as a result of the disease, if the virus does become endemic we should still try to prevent as much infection as possible.
A vaccine could provide a way to end the pandemic, but with no prospect of natural herd immunity, we could well be facing the threat of COVID-19 for a long time to come.
This is why it is imperative to continue to use public health measures. Everyone should continue social distancing, wearing masks, washing hands, and wearing gloves when necessary to reduce the spread of the virus. If we all follow these simple steps daily we can all help lower any outbreaks more effectively.