New Vaccines and ADE

Vaccines – Because of this week’s announcement about vaccines, lots of folks are asking me about it.  I’ll give you my thoughts.  I am not an immunologist, I’m a molecular biologist specializing in infectious disease testing, so my thoughts on vaccines are informed, but not expert.

As I’ve discussed before, I’ve been pessimistic about COVID vaccines, mostly because of the phenomena of Antibody Dependent Enhancement, or ADE (link below).  This is the phenomena in which some virus can use antibodies against a similar but not identical virus to infect the immune system and cause more severe disease.  As this relates to a vaccine, a person given a vaccine could gain immunity against virus very similar to the vaccine given, but less similar strains may still infect and cause more severe illness.  This has been my concern about both vaccines and the herd immunity approach. 

In the past few months, however, a trickle of known cases have come out about people who have been reinfected with SARS-2. Some of these patients have had worse symptoms, and some more mild.  It’s also evident that they are not being infected with the same strain they had before, but by a different strain.  If all this is true, then the ADE experiment is already being done.  And it looks like while some experience more severe illness, not all do, and reinfection appears to be rare, despite several circulating strains.

This week Pfizer announced that studies with their vaccine show 90% effectiveness in preventing COVID infection.  My hesitation with vaccines has always been about ADE.  It’s still not well known if ADE will play a significant role, but if it doesn’t, then perhaps there is reason for hope.

All medications and vaccines carry the risk of side-effects and harm.  However, I’m actually becoming cautiously optimistic about a COVID vaccine.

Some technical info about vaccines.  There are actually several kinds of vaccines.  Various developers tried different pathways to a COVID vaccine, and several kinds are in trials right now.

Killed vaccines – These are vaccines that have been deactivated or broken down into various parts and then injected into the body.  They cannot replicate and degrade in the body, so parts are attached to molecules called adjuvants that serve to boost their visibility to the immune system. 

Attenuated vaccines – These are live viruses that have been engineered to cause infection, but with no or mild symptoms.  Some are other viruses like Adenovirus which are symptom free, but produce viral proteins that your body can recognize and raise a response against.

RNA vaccine – This a brand new kind of vaccine that has been in testing for years.  Several SARS-2 vaccines are of this kind, and are the first potential viable candidates ever.  The patient is injected with a piece of RNA that codes for a viral protein. The RNA enters a cell and temporarily causes the cell to make the viral protein. RNA naturally degrades rapidly in the body and does not persist or permanently change the patient’s genetic material. This promising technique has the potential to generate new and more effective vaccines in the future.

Personally, I’m still taking a wait and see approach.  Vaccines will probably not be available to the general public for few months.  By then we may know more about how people are responding.

Don’t fear, but be smart!

1 thought on “New Vaccines and ADE

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