#vaccinationschedule Finding a covid-19 vaccine that ends the crisis is a hope that thousands of people dream about.
People are tired of living in fear and not being able to go out on the street with peace of mind.
There are currently more than 150 candidates developing in the world, so it is possible that at some point an effective enough to curb the number of infections. Even if it is partially.
However, although there are signs to be optimistic, there is no guarantee that a vaccine good enough to stop the pandemic will be found in the near future.

For this reason, considering all possible scenarios and having in mind a plan B in which there is no vaccine is a necessary exercise of accountability and transparency.

Unfortunately, if anything we can be almost certain in this pandemic is that this coronavirus has come to stay.

Creating the false hope that we will soon have an effective vaccine or treatment against covid-19 can be a double-edged sword that could cause great disappointment if expectations are not met.

On the other hand, excessive optimism could create a sense of false security and lead to a relaxation of virus prevention and control measures that have proved effective in preventing its spread.
Vaccine development presents many challenges to making them safe and effective, and this is no exception.

Therefore, it is important to know the limitations and problems that can be encountered so as not to fall into excess confidence in their effectiveness and delivery times.

These are 10 of the many reasons why you have to be realistic and not expect a miraculous vaccine to appear that will immediately free us from this pandemic.

1• RUSH IS NOT GOOD
The normal process for making a vaccine is between 10 and 15 years. We can't expect to have a perfect one in less a year and that will allow us to automatically return to our previous life.

For example, the shortening we are seeing from the preclinical research phase in which the vaccine is studied in cell cultures and in animals is somewhat unusual and a reflection of the urgency to find the vaccine.

2• HAS TO PROTECT IN HUMANS
It's easy to say, but that's where most candidates usually fail.

A vaccine can be very well designed, safe, 100% protect in animal models, and induce a strong immune response and neutralizing antibodies, but offer a much lower level of protection than expected when tested in humans.

3• WANTING IS NOT ALWAYS POWER
In 1984, when the human immunodeficiency virus (HIV) was identified as responsible for the AIDS pandemic, the United States Secretariat of Health and Human Services stated that the vaccine would be available within 2 years. Today, 36 years later, there is still no vaccine.

Vaccine development does not always bear fruit. Although comparing HIV with this novel coronavirus is not the most accurate because they are very different, there are times when - however much it is sought - there is no way to develop an effective vaccine.

In fact, although there are good candidates for vaccine with promising results in animal models, so far no vaccine is available for any of the other coronaviruses that affect humans.

4• ADVERSE EFFECTS

Vaccines, like any medicine, can cause side effects.

One of the main problems that researchers face is the potentiation of Antibody Dependent Infection, better known as ADE.

This is an unwanted reaction in which the generation of antibodies to an infectious agent, for example using a vaccine, results in much worse symptoms. This means that the disease is enhanced in case of infection with the virus.

5• LARGE-SCALE PRODUCTION

One of the main challenges we will encounter if an effective coronavirus vaccine is its large-scale mass production to reach as much of the world's population as possible.

We're talking about producing billions of doses.

That does not take into account that many of the vaccines being studied require two doses per individual.

In addition, another added problem would be to massively produce sufficient doses without affecting the production of other important vaccines.

6• DISTRIBUTION OF THE VACCINE
Imagine that an effective vaccine against Sars-Cov-2 is developed and produced on a large scale.

The next problem would be its efficient delivery to billions of people around the world. It's no use to have a vaccine if it doesn't reach the end user.

Achieving efficient global distribution poses major logistical challenges. Vaccine companies, governments in different countries and transport companies should work together and agree.

Most vaccines should generally be kept refrigerated at a temperature of between 2 °C and 8 °C.. For this reason, one of the main challenges to be overcome would be not to break the cold chain.

This problem could be aggravated, because vaccine candidates require an ultra-cold chain with temperatures close to -70 °C.

7• NATURAL IMMUNITY SEEMS TO LAST SHORTLY
For months there have been announcements of possible reinfections circulated from different parts of the world. Today it is already a fact that people who have passed the disease can get infected again.

This is relatively common in infectious diseases. In fact, there is no described respiratory viral disease in which no reinfections occur.
One possible explanation would be that, as for other coronaviruses that infect humans, the presence of antibodies is gradually disappearing within a few months after infection.

The main problem with reinfections is that, although vaccines usually develop a stronger immune response than natural infection, the expected results would not be the best if it is already known beforehand that natural immunity is not long-lasting.

Although the role of the cellular response in vaccinations and its relevance in protecting against infections remains to be seen, it seems that it would most likely have to be re-vaccinated from time to time.

8• AGE IS IMPORTANT
A challenge for this vaccine is that older people are more susceptible to infection and carry a particularly high risk of serious or lethal disease.
Therefore, protecting adults over 60 years of age from covid-19 is one of the most important goals of researchers.

The main problem is that as we get older, our immune system becomes less efficient and vaccines are less effective.

9• TECHNOLOGY TOO RECENT
Most of the vaccines we use involve the injection of a weakened, inactivated virus or simply virus components that are produced and purified in the laboratory.

However, many of the vaccine candidates that are now being tested in humans are based on relatively recent genetic technologies. They are known as “genetic vaccines," which can be DNA or RNA.
In this case, instead of inoculating whole viruses or subunits of the virus to induce an immune response as traditional vaccines do, the idea is to make our own body produce the virus protein.

To do this, we would directly inject the part of the viral genetic code containing the instructions for making the protein of interest.. Finally, our cells would produce this protein alerting the immune system.

Genetic vaccines have many advantages. For example, lower cost and the need for a much lower production infrastructure.

The main problem is that so far none have been marketed for humans, so their effectiveness is still to be checked.

10• PROTECTION? YES, BUT PARTIAL
Everything seems to indicate that in the event of a successful candidate, the first vaccines would partially protect against infection, immunity would be short-lived and would not work for everyone..
However, it is always better to have a partially functioning vaccine than to have none.

It would be very useful to protect part of the population and slow down the growing rate of infections. In addition, having such different candidates in development it is possible that different objectives could be met.

On the other hand, more complex vaccines may be developed in the distant future that will achieve better results.
In short, although unprecedented effort and preliminary results may invite optimism, reality can be very different.

Therefore, it is necessary to avoid falling into excess confidence and to consider all possible scenarios.

Finally, it is important to remember that until the pandemic does not remit it is of vital importance to respect the basic health protection measures that actually work to prevent infection:

• Correct use of the mask.

• Wash your hands frequently with soap and water.

• Maintain social distancing.