First of all, I believe and support that vaccines saves lives. I am not an anti-vaxxer. I’m just concerned with the vaccine for specifically this virus SARS-CoV-2. #VaccinesSavesLives
Currently, I’m still not very optimistic with vaccines because of these reasons:
- Antibody-Dependent Enhancement (ADE)
a. Antibody-dependent enhancement means that having antibodies to a certain disease after a prior infection or immunization makes the immune response to a disease hyperactive. Hyperactive immune response can destroy the body more than it helps in removing the virus. This phemonenon is seen in the Dengue virus, as well as Coronaviruses.
b. Any peptide-based vaccine is at risk of ADE. However, Moderna mRNA vaccine mitigates this risk and other vaccines show initial promising results. I’m cautiously hopeful for now.
c. “However, earlier studies on SARS and MERS vaccine candidates have pointed to risks of antibody-dependent enhancement (ADE) of infection. In the former, presence of non-neutralizing antibodies contributes to increased infections whereas the latter can lead to life-threatening allergic inflammations. While there is no clear evidence yet, immunological data from patients may point toward possible ADE for SARS-CoV-2, suggesting that high IgG titers correlate with worse outcomes.” – excerpt
- Duration of Immunity (for herd immunity from vaccines and natural infection)
a. Yes, it is well established that neutralizing antibodies are formed. Question is, HOW LONG do they last?
b. Several journals and news articles have reported that they only last for 2-3 months. This has implications on vaccination.
c. For example, flu vaccines should ideally be given YEARLY because of the virus’s rapid rate of mutation. And even if we have yearly vaccines, a genetic shift can cause a pandemic, such as a 2009 Influenza AH1N1 pandemic.
d. SARS-CoV-2 has SEASONAL features. Waves come in seasons and multiple times in a year.
- Vaccine Production
a. Traditionally vaccines are produced using mammalian cells. This is established; however, this is expensive.
b. Cheaper alternatives include yeasts, bacterial cells, insect cells, plant cells, but issues such as non-human glycosylation, human pathogen contamination – make safety and efficacy of vaccines questionable.
c. “Large-scale production and worldwide distribution of a potent COVID-19 vaccine(s) will be governed by economic disparities between nations. When demand exceeds supply, developing countries are in a disadvantaged position for the bidding contest to procure the highly sought after vaccine, a situation already seen with personal protective equipment and other critical goods even between industrialized nations. Therefore, it is critical to also consider technologies and platforms suited for developing countries.” – excerpt
- Vaccine Distribution
a. Conventional vaccines require cold chain infrastructure for distribution, meaning, vaccines need to be CONSTANTLY stored in cold containers for them to maintain their efficacy. Alternatives to cold chain infrastructure are implants and microneedle patches, but these are not yet established. Tropical countries, which are mostly developing countries and have a hot climate, are at risk of vaccine loss.
b. “The WHO also reported that 2.8 million vaccines were lost in five countries due to cold chain failures, and less than 10% of countries met WHO recommendations for effective vaccine management practices. While some lyophilized vaccines are available that may be stored at room temperature, such solutions are difficult to produce and present challenges for the healthcare professionals who must reconstitute them on site.” – excerpt
c. The more expensive, less-ADE-prone, safety-established, vaccines might only be available for the ruling class and not the poor. The average citizen and the poor, especially in a developing country, will be forced to take the less safe, less efficacious, more-ADE-prone vaccine. (Also note the discrepancy on access to cold chain infrastructure between the rich and the poor, the urban and the rural.)
d. Note as well the deplorable political condition of our country as mentioned in a previous post.
Reference Journal: Shin, M.D., Shukla, S., Chung, Y.H. et al. COVID-19 vaccine development and a potential nanomaterial path forward. Nat. Nanotechnol. (2020). https://doi.org/10.1038/s41565-020-0737-y
Photo taken from the said journal.
Other comments:
- In my humble opinion, I’m almost certain that China will win this vaccine race. Note the discrepancy in how China funds biomedical research versus U.S. China has filed more patents in life sciences last year than the U.S. [Reference: CNN Report: https://youtu.be/0dkLugEf47c%5D
- Even if the vaccine is produced in a Western country, the materials needed to mass produce the vaccine will in one way or another come from China. In other words, China controls the means of vaccine production. [Referenece: EconomicsExplained: https://youtu.be/b07eafPe7pY%5D
Regarding ADE and Dengvaxia:
The official recommendation was “not to give Dengvaxia to those who were infected before because it increases the risk of severe dengue.” This is why I suspected ADE to play a role.
However…
“In patients who have not had dengue before, the risk of severe dengue increases from 2 out of 1,000 to 5 out of 1,000. It’s a low number, but it’s significant. However, it is same as that of somebody who has already had dengue once and did not get the vaccine.”
“Vaccinating patients who have had dengue before, the risk of severe dengue goes down from 5 out of 1000 to less than 1 out of 5000.”
Reference: ABS-CBN News. 2020. Dengvaxia Helpful If ‘Used Properly’: Infection Specialist. [online] Available at: https://news.abs-cbn.com/news/08/08/19/dengvaxia-helpful-if-used-properly-infection-specialist [Accessed 20 July 2020].