Saturday, September 18, 2021

COVID-19 vaccines




TellZim Reporter

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

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
many potential
COVID-19 vaccine candidates currently in development

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

  • 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 
    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.

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?

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.

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?

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

different types of potential vaccines for COVID-19 are in development,

  • 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.

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. Source WHO


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