![]() Various techniques tame the virus for use as a vaccine, rendering it “inactivated” – a virus isn’t considered alive, so it can’t be killed. Each category includes multiple candidate vaccines – I quickly gave up trying to mention all the companies. Here’s how they work, roughly organized by decreasing size. The candidate COVID vaccines can be grouped in various ways, lumping molecular techniques or defining them more granularly. And DNA or RNA sequences can be tweaked – “optimized” – to elicit specific responses. Proteins, DNA, or RNA can’t cause infection and fit into platforms developed in recent years to treat other emerging infectious diseases. The vaccine roster includes traditional strategies like entire disabled viruses that fool the immune system and molecular approaches that instruct it. ![]() Health and Human Services offers a vaccine primer here, and the Coalition for Epidemic Preparedness Innovations ( CEPI) website describes vaccine candidates. The WHO maintains a list and STAT News’s Covid-19 Drugs & Vaccine Tracker is also excellent. lists more than 225 entries, but half aren’t really vaccines or are revamped old ones. The global effort to develop a COVID-19 vaccine is unprecedented. Vaccines can deliver spike protein, the DNA sequence that tells the human cell to make the corresponding mRNA, or the mRNA sequence directly, unleashing the instructions for cell parts to come together and build the protein. For the coronaviruses, the most pursued antigens are the triplets of spike proteins that festoon their surfaces like a crown ( “Covid 19 Vaccine Will Close in on the Spikes” from DNA Science back at the beginning of the pandemic.) And that’s where the central dogma comes in. Like identifying a criminal from a distinguishing facial feature, the immune system – a mobile army of white blood cells – zooms in on surface features, or antigens, of a virus. All present a pathogen or a part of one to the immune system – but they do so differently. Today, understanding the flow of genetic information guides vaccine invention. So important is this trajectory that geneticists have called it “the central dogma” since Francis Crick’s team deciphered the details in 1961. But how many can quickly recite the three levels of genetic information: DNA, RNA, and protein?Ī gene is a sequence of DNA building blocks that encodes a protein, via an intermediate molecule, messenger RNA (mRNA). People know sun-moon-earth, the three types of rocks, the three types of subatomic particles. While grasping the basics of epidemiology relies on common sense and logic – masks minimize spread of virus-laden aerosols and droplets – the immunology and genetics behind vaccine action may be less familiar. The public has had a crash course in biology these past six months. Understanding how it all happens isn’t like learning “how the sausage gets made.” Knowledge may quell fears. The vaccines work in what can seem to be mysterious ways, but all present a pathogen in some form, or its parts, to alert the immune system to mount a response. I hope more than one is successful, with equitable distribution,” Fauci said. “It’s a misperception that vaccine development is a race to be a winner. Having choices would provide options for people not covered by some of the vaccines, like those over age 65 and people with certain medical conditions. If the body can mount an immune response and clear the virus in natural infection, that’s a pretty good proof-of-concept that you’ll have an immune response against a vaccine.” ![]() The overwhelming majority of people make an immune response that clears the virus and recover. “I’m cautiously optimistic that with the multiple candidates with different platforms that we’re going to have a vaccine with a degree of efficacy that would make it deployable. The ultimate voice of scientific reason, Anthony Fauci said in a media webinar: But I think some of the hesitancy might be due to confusion over how so many different vaccines can target the same pathogen – and why this is a good idea.
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