Wikipedia:Reference desk/Archives/Science/2020 October 21

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October 21

Yearly influenza vaccine development time vs. other vaccines

How come it is possible to develop and deploy a different influenza vaccine yearly (or twice yearly, 1X per hemisphere), but the fastest effective vaccine took 5 year to develop and some COVID-19 vaccines could take at least 18 months (or longer)?

Doesn't the influenza vaccine need thorough testing? Couldn't it cause serious side-effects or even death? --Bumptump (talk) 12:48, 21 October 2020 (UTC)

What you refer to as 'the' influenza vaccine is actually a mixture of several vaccines, each of which is most effective against one (or a small number) of the many strains of many viruses which can cause influenza. Most of these viruses and strains have been known for a long time (though new strains crop up from time to time), and each of their specific vaccines are already well known and well tested, as are various combinations of them.

However, the actual mixture has to be different every year, because every year different virus strains become the most prevalent (a bit like a sports league). Medical scientists have to predict, many months in advance, which ones will be the most prevalent, decide which vaccines should be combined in the forthcoming winter season's "flu shot", and then cultivate enough of them to make sufficient doses.

Although the combination of vaccines in a "flu shot" will likely improve general resistance against other influenza strains and viruses that are not their primary target, it's always possible to catch a rare virus or strain that won't be sufficiently combatted, and develop influenza anyway.

Any vaccine has the potential to cause serious side effect in a small proportion of people, because people's immune and general physiological systems vary (and ultimately everyone is unique), but the number so affected is far smaller than those who would be killed or seriously incapacitated by actually contracting influenza if vaccines were not used (see Influenza vaccine#Safety). {The poster formerly known as 87.81.230.195} 2.218.14.156 (talk) 14:29, 21 October 2020 (UTC)

It's also a matter of "starting from scratch" vs not. The different flu shots that you get year to year are all very similar to each other. That is, they are all manufactured the same way/under the same conditions (be that eggs or what have you), which has already been thoroughly tested and deemed safe. They all target the same main types of antigens, which are also well tested and safe. The variations between them are very minor. For example, if inactivated virus, the virus used is exceedingly similar in any given year, with minor variations on the antigens that the immune response needs to recognize. Contrast this with developing a vaccine against a truly novel infection, such as SARS-CoV-2, and that doesn't hold up. The antigens are completely different (influenza doesn't have spike proteins targeting ACE2 receptors, for example), and that means we don't know for certain, the way we do with flu shots, how a vaccine will interact with the body. A completely different vaccine also means potentially a completely different production process as well. These are all non-variables in annual flu shots, but are present issues when developing a truly new vaccine for something else. Now, if someone wanted to develop a truly new flu vaccine, maybe one that didn't require new annual versions (and I've seen some research in that direction), you wouldn't see the development take less than a year. --OuroborosCobra (talk) 17:19, 21 October 2020 (UTC)

• Picture a carpenter who builds tables for a living. When he started, he had to learn how to build a table from scratch. Design a table. Test it out to make sure it worked. Try different designs. However, after several decades of doing nothing but building tables, he's gotten really good at building tables. He has a hundred different designs memorized, he can do custom work because he knows all of the different ways to make a table, etc. etc. Even if you give him an idea for a table to make he's never done before he still knows TABLES, so he can build it without much trouble. One day, a new contract comes in asking him to build a cabinet. Like with walls and doors and shelves. He's NEVER built a cabinet before. Now, he's a carpenter, so he'll figure it out eventually, but it's going to take him some time to get up to speed. He has to learn a whole new way of making things. He's going to try to make a cabinet, and maybe the first 2-3 attempts are no good so he'll need to throw them away. Eventually, he'll get it, but it will take him much more time than a table would. Now, replace the word "carpenter" with "biomedical industry" and the word "table" with "flu vaccine" and the word "cabinet" with "Covid vaccine" and you'll understand. --Jayron32 16:06, 22 October 2020 (UTC)

• ... and replace the phrase "throw them away" with "potentially kill the test subjects". Matt Deres (talk) 16:33, 22 October 2020 (UTC)

Finding, in one's first two to three attempts at producing a vaccine, that it is no good is sad but does not create a need to "potentially kill the test subjects", I should think.  --Lambiam 20:27, 22 October 2020 (UTC)

Agreed with Lambian. It's rather rare for test subjects to die as a result of the vaccine trials. Even the current death in the Oxford trial has been determined to be a test patient on the placebo, and thus the vaccine didn't kill them. I guess add some sort of step into the carpentry like CAD, where designs of this cabinet are tried out before building the real thing. You may still need to do multiple real builds before you get it right, but you'll hopefully not have any cabinets that collapse from their own weight first. --OuroborosCobra (talk) 22:09, 22 October 2020 (UTC)