Covid Vaccine Information

medical vaccination world

Active treatment for cancer can reduce the effectiveness of the immune system during therapy and for a short time afterwards. People who have weakened immune systems are at greater risk of getting infections such as COVID-19. Understandably many cancer patients and survivors are anxious to learn about the Covid-19 vaccine. You can always talk to your healthcare team for any questions or concerns you may have over the Covid-19 vaccine.

COVID-19 Vaccine

Comirnaty, the recently approved vaccine developed by Pfizer-BioNtech, has been tested in tens of thousands of people around the globe and already given to millions more.  The Moderna COVID-19 has also been approved subsequent to 15,000 people receiving the active vaccine in a placebo controlled trial. As with all other vaccines, these studies found that the mild pain, redness, headaches etc. happen somewhat commonly among those receiving the vaccine and at rates similar to those seen in other vaccines.  There have been very small numbers of reports of more severe allergic-type immune reactions among those with histories of more severe allergy, again such reactions are known to occur with all vaccines.  This is why vaccines are administered by trained health professionals who know how to manage allergic-type reactions.  In the tiny number of cases where this has happened, the individuals affected all made complete recoveries.

Similar findings are being found with the other vaccines that are currently emerging from late stage clinical trials and which are undergoing regulatory scrutiny.  Each vaccine uses variations or different technology to generate immunity and hence must be separately tested to ensure safety.

Independent and ongoing safety and usefulness assessment are made by regulatory agencies to ensure that any vaccine is being used appropriately. 

Why get a vaccine?

Vaccines benefit those who receive them but the bigger benefit is actually seen in our community as a whole.  Low rates of infections (which high uptakes of vaccines provide) allow the incredible people in our health service to focus on the other vital aspects of our health system.  High rates of illness compromise that.  Hence, if we want to be able to easily get a doctor’s appointment or make sure a loved one can get treatment for a disease reasonable quickly we must all play our part in driving the infection from our community through vaccination.

While there are lots different types of vaccines available, they all work on the principle of training the immune system to recognise key infection proteins but without giving the person the actual infection.  Hence, vaccines are simply a way to mimic the natural processes of immunity without the risk of getting sick from the illness.

How long will it take before I’m immune?

With both the vaccines undergoing clinical trials and those recently approved it appears that roughly 4-6 weeks is needed for the maximum level of immunity to be established.  The currently approved vaccines require two doses 3-4 weeks apart to optimise this immunity.

When a person’s immune system is exposed to the first dose a number of adaptations occur in their immune system over several days which result in the gradual emergence of an efficient immune response targeted at the SARS-CoV-2 virus.  The second dose helps encourage the immune system to further optimise and grow cells and antibodies which are the most specific and efficient at targeting and preventing the infection from causing disease in the person receiving the vaccine.

Everyone’s immune system is slightly different and hence there can be come variation between individual people as to how well they can produce a useful immune response.  The information to date for both of the approved vaccines is that if 20 people were to be immunised with 2 doses of either between 18 and 19 of those 20 would not get a serious infection if exposed 6 weeks or later to COVID.  This 90-95% efficiency is quite high compared to some commonly used vaccines and conversely no vaccine gives 100% protection to 100% of people.  Certain cancers or cancer treatments will impact the immune system and may be expected to either temporarily or permanently reduce the level of immunity associated with the vaccine below that of a non-cancer peer.

Are COVID vaccines safe?

The decision as to whether any medicine is regarded as safe or not is made by expert independent medicines regulatory agencies.  In Ireland, decisions on medicinal safety are first made by independent experts in the European Medicines Agency (EMA) and these are then followed up by the medicines safety experts in the agency responsible for medicines oversight in Ireland – the Health Products Regulatory Authority (HPRA).   These agencies are responsible for all of our medicines and look at all aspects of safety, including production of a medicine, as well as the evidence as to how well it might work.  Once a decision is made that a medicine is safe and work, these agencies also monitor the impacts of that medicine for as long as it is in use.  For a medicine to be approved independent experts have decided that all of the evidence indicates that the vaccine is indeed safe.

Are there other considerations for those with cancer?

Patients with cancer are justifiably nervous of lumps.  In a small percentage of those who have been vaccinated, local glands have occasionally swelled for a time.  Patients are also counselled and are often hyper-vigilant for increases in temperature, chills and fevers.  In certain forms of cancer or particular types of cancer treatment these can be important signs of infection, which can be serious.  Hence, it is possible that occasional side effects, which would not be noteworthy for those not being treated for cancer, could cause undue anxiety against the backdrop of signs that those in the treatment community must be attentive for.  Where side effects do occur, they are more commonly described with the second dose and hence patients and healthcare professionals might do well to discuss the possibilities of these happening and options for reassurance should they arise.

You can read an in-depth piece on Covid-19 vaccines and cancer from our Director of Research Dr Robert O'Connor here

More information on the COVID-19 vaccine can be found here.

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