Vaccines

Coronavirus disease (COVID-19):
Vaccines
Q&A

Is there a vaccine for COVID-19?
Yes.
There are three COVID-19 vaccines for which certain national regulatory authorities have authorized the use.
None have yet received WHO EUL/PQ authorization but we expect an assessment on the Pfizer vaccine by the end of December and for some other candidates soon thereafter.
Large studies of 5 vaccine candidates efficacy and safety results, including these three (and for Moderna and AstraZeneca), have been publicly reported  through press releases but only one (AstraZeneca) has published results in the peer reviewed literature.,
We expect more such reports in the near future.  
It is likely that additional candidates will be submitted to regulatory authorities for approval.
There are many potential COVID-19 vaccine candidates currently in development.
Once vaccines are demonstrated to be safe and efficacious, they must be approved by national regulators, manufactured to exacting standards, and distributed.
WHO is working with partners around the world to help coordinate key steps in this process, including to facilitate equitable access to safe and effective COVID-19 vaccines for the billions of people who will need them.



When will COVID-19 vaccines be ready for distribution?
The first COVID-19 vaccines are beginning to be introduced in countries.
Before COVID-19 vaccines can be delivered:
    The vaccines must be proven safe and effective in large (phase III) clinical trials.  
Some large clinical trials of COVID-19 vaccine candidates have reported encouraging preliminary results, and many other potential vaccines are being developed.
    A series of independent reviews of the efficacy and safety evidence is required, including regulatory review and approval in the country where the vaccine is manufactured, before WHO considers a vaccine product for prequalification.
Part of this process also involves the Global Advisory Committee on Vaccine Safety.
    In addition to review of the data for regulatory purposes, the evidence must also be reviewed for the purpose of policy recommendations on how the vaccines should be used.
    An external panel of experts convened by WHO, called the Strategic Advisory Group of Experts on Immunization (SAGE), analyzes the results from clinical trials, along with evidence on the disease, age groups affected, risk factors for disease, and other information.
The panel then recommends whether and how the vaccines should be used.
    Officials in individual countries decide whether to approve the vaccines for national use and develop policies for how to use the vaccines in their country based on the WHO recommendations.
    The vaccines must be manufactured in large quantities, which is a major and unprecedented challenge – all the while continuing to produce all the other important life-saving vaccines already in use.
    As a final step, all approved vaccines will require distribution through a complex logistical process, with rigorous stock management and temperature control.
WHO is working with partners around the world to accelerate every step of this process, while also ensuring the highest safety standards are met.



Will COVID-19 vaccines provide long-term protection?
It’s too early to know if COVID-19 vaccines will provide long-term protection.
Additional research is needed to answer this question.
However, it’s encouraging that available data suggest that most people who recover from COVID-19 develop an immune response that provides at least some period of protection against reinfection – although we’re still learning how strong this protection is, and how long it lasts.
Most COVID-19 vaccines being tested or reviewed now are using two dose regimens.



How likely is it that safe, effective vaccines for COVID-19 will be developed?
WHO is cautiously optimistic that safe and effective vaccines for COVID-19 will be successfully developed.
There is a robust pipeline of potential vaccines in development, and some have already advanced to large (phase III) clinical trials based on promising early data.
But for now, we can’t be certain if or when a COVID-19 vaccine will be available.
That is why we must not rely on a future vaccine to fight this pandemic – we must use all the tools we already have at our disposal, such as testing, contact tracing, physical distancing, and the use of masks.



How quickly could COVID-19 vaccines stop the pandemic?
The impact of COVID-19 vaccines on the pandemic will depend on several factors.  
These include factors such as the effectiveness of the vaccines; how quickly they are approved, manufactured, and delivered; and how many people get vaccinated.
Most scientists anticipate that, like most other vaccines, COVID-19 vaccines will not be 100% effective.
WHO is working to help ensure that any approved vaccines are as effective as possible, so they can have the greatest impact on the pandemic.



What types of COVID-19 vaccines are being developed? How would they work?
Scientists around the world are developing many potential vaccines for COVID-19.
These vaccines are all designed to teach the body’s immune system to safely recognize and block the virus that causes COVID-19.
Several different types of potential vaccines for COVID-19 are in development, including:
    Inactivated or weakened virus vaccines, which use a form of the virus that has been inactivated or weakened so it doesn’t cause disease, but still generates an immune response.
    Protein-based vaccines, which use harmless fragments of proteins or protein shells that mimic the COVID-19 virus to safely generate an immune response.
    Viral vector vaccines, which use a virus that has been genetically engineered so that it can’t cause disease, but produces coronavirus proteins to safely generate an immune response.
    RNA and DNA vaccines, a cutting-edge approach that uses genetically engineered RNA or DNA to generate a protein that itself safely prompts an immune response.
For more information about all COVID-19 vaccines in development, see this WHO publication, which is being updated regularly.



Will other vaccines help protect me from COVID-19?
Currently, there is no evidence that any existing vaccines will protect against COVID-19.
However, scientists are studying whether some existing vaccines –such as the Bacille Calmette-Guérin (BCG) vaccine, which is used to prevent tuberculosis– are also effective for COVID-19.  
WHO will evaluate evidence from these studies when available.


The Source:
https://www.who.int/news-room/q-a-detail/coronavirus-disease-(covid-19)-vaccines