In this blog we will discuss differences between four licenced Covid19 vaccines including Pros and Cons of each type.
Bharat Biotech :
-Inactivated whole virus vaccine: two doses 4 weeks apart
Pros:
-Generally considered a safe vaccine platform
-Time tested and established platform used for various other existing vaccines such as Polio.
-Attacks whole virus including Spike protein, nucleocapsid protein etc. In theory, may tackle variants better due to this property.
-Safety data from phase 1 and 2 trials matches other vaccine candidates
-Uses strain of virus prevelant in India and phase 3 trial enrolled over 25,000 candidates in India
-Stored at normal fridge temperature
-Large production and distribution facilities
-Affordable price approx $ 4 per dose
Cons:
-Efficacy can be affected adversely by the extent to which viral proteins are denatured during process of inactivation and data is not available at this time
-Inactivated vaccines are typically mildly immunogenic. For this reason they often require adjuvant and multiple boosters.
-Vaccine roll out will be in trial mode. Will require signed consent and follow up.
Oxford Vaccine
-DNA Recombitant Vector Vaccine: two doses 4-12 weeks apart
Pros:
-Efficacy data published at 62% which is above the WHO minimum standard of 50 %
-Platform used previously for Ebola virus vaccine
-Stable at normal fridge temperature for six months
-Large production and distribution facilities
-Affordable price approx $ 4 per dose
Cons:
- Study was primarily done abroad and had flaws including half dose given to a subset of patient in error.
-Marketting of vaccine has been misleading at times with use of an average efficacy number of two different dose regimes with large variation in sample size.
-Subsequent UK government decision to extend booster from 4 weeks to 12 weeks has been criticised by FDA and others as unscientific. Virologists suggests that large scale suboptimal immunity could cause a rise in escape variants of the virus.
-Live
vaccine should be avoided in pregnant, immune compromised etc although
they are likely safe since virus has been rendered replication
deficient.
-This vaccine uses a monkey adenovirus vector ECC-201 while rivals Johnson and Sputnik use human adenovirus vectors.
There is a question whether the few cases of neurological complications
reported during trials were immune dysregulation triggered by zoonotic
virus vector although the incidence of these cases was equal to normal
population.
-There are some signals that this vaccine may be less efficacous at preventing symptomatic illness in case of variants although prevention of serious disease and death appears to be maintained.
Pfizer / BioNtech:
-mRNA Vaccine: two doses 3 weeks apart
Pros:
-95 % efficacy data for disease
-can be produced quickly and adapted for mutations
-approx 5 million doses of mRNA vaccines have now been administered with the only safety signal emerging being slightly higher risk or allergic reaction
-multinational production capacity
Cons:
-11 cases of severe allergic reaction have been reported after one million doses which equates to about 1 in every 100,000 doses. This may be related to chemicals used in lipid nanoparticle vehicle and is regarded as an acceptable level of risk for most vaccines.
-expensive at about $20 a shot
-minus 70 degree celcius storage makes logistics difficult and may also pose reduced efficacy risk if not handled adequately
-brand new technology which adds possibility of long term side effects ( highly unlikely )
Moderna
-mRNA vaccine: two doses four weeks apart
Pros:
-94 % efficacy for disease and 100 % efficacy for serious disease
-80% efficacy after the first dose
-can be produced quickly and adapted for mutations
-at present appears to have fewer serious allergic reactions than Pfizer, .
-approx 5 million doses of mRNA vaccines have now been administered with the only safety signal emerging being slightly higher risk or allergic reaction
Cons:
-most expensive vaccine at $30 a shot
-limited production facilities
-company with limited experience of producing vaccine
-minus 30 freezer storage poses moderate logistic challenge
-more reactogenic than Pfizer: more incidence of local / systemic side effects but does self resolve.
-brand new technology which adds possibility of long term side effects ( highly unlikely )
Promising Covid19 Vaccines in Pipeline
India: Zydus Cadilla: DNA Vaccine
USA: Johnson & Johnson : Single dose Adenovirus Vector
Non-Covid Vaccinations
While you are waiting for your shot, there are some other options to consider !
-Annual Flu Vaccine
-MMR / MMRV / Varicella booster if antibody titres are low
-Pneumonia and Shingles vaccination in those above age 50
This study found an inverse relationship between MMR vaccine induced Mumps antibody titres and severity of Covid19 disease. I recommend that patients above age 40 consider checking MMRV antibody titres. Low titres would allow a live vaccine booster shot, which has been postulated to boost innate arm of immune system.
https://mbio.asm.org/content/11/6/e02628-20
This
study from Mayo Clinic, USA demonstrates that various vaccinations are
correlated with less SARS-COV2 infection, particularly Pneumonia
Vaccination. My opinion is that considering that upto 10 % of Covid19
can be complicated by secondary bacterial pneumonia, it makes sense for
those who are eligible for Pneumonia vaccination ( Prevnar13 followed by
Pneumovax23 after two months in patient above age 50 ) to take it.
https://www.medrxiv.org/content/10.1101/2020.07.27.20161976v2
This clinical trial recruiting in Oklahoma, USA to investigate whether Shingles Vaccination may boost immune system vs SARS-COV2. It has been documented that Covid19 can lead to Shingles and so I recommend that patients who can now receive Shingles vaccine ( age above 50 ) should take it.
https://clinicaltrials.gov/ct2/show/NCT04523246
This study from Netherlands cites cell studies which show better immune cytokine response in individuals who have received Flu vaccination vs SARS-COV2 and lower incidence of Covid19 in hospital staff who received Flu vaccine compared to those who had not.
https://www.medrxiv.org/content/10.1101/2020.10.14.20212498v1.full-text
This Italian Observational data paper influenza vaccination coverage rates correlated negatively with adverse COVID-19 outcomes
https://www.mdpi.com/2076-393X/8/3/535/htm
This Italian regional analysis demonstrated that percentage of COVID‐19 deaths decreased for each unit percentage of adults greater than 65 years old vaccinated against influenza
https://onlinelibrary.wiley.com/doi/10.1002/jmv.26120
INFORMATION & DISCLAIMER:
I obtained my primary medical education from India and post graduate MD in Family Medicine from the United Kingdom. After working in the NHS for 15 years, I moved to Canada five years ago. As a Family Physician, my specialty is engaging patients, interpreting medical information for them, guiding them through their health journey, promoting wise health choices and encouraging early detection and management of disease. The information on this blog is accurate as per time of publishing and patients should check the main blog for updates. Scientific information and evidence changes dynamically and my opinions would change accordingly. The recommendations on this blog are not prescriptions and any patients considering these should consult with a physician to check if these are applicable to their unique case. Patient confidentiality must be upheld at all times and any patients wishing to discuss specific medical scenarios on social media are requested to do so anonymously in 'third party' sense.
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