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posted by martyb on Sunday January 12 2020, @01:53PM   Printer-friendly
from the ready?-heave! dept.

In the last few months, schools all over the country have closed because of outbreaks of norovirus. Also known as stomach flu, norovirus infections cause watery diarrhea, low-grade fever and, most alarming of all, projectile vomiting, which is an extremely effective way of spreading the virus.

Norovirus is very infectious and spreads rapidly through a confined population, such as at a school or on a cruise ship. Although most sufferers recover in 24 to 48 hours, norovirus is a leading cause of childhood illness and, in developing countries, results in about 50,000 child deaths each year.

Interestingly, not everyone is equally vulnerable to the virus, and whether you get sick or not may depend on your blood type.

[...] The naked capsid coat is one factor that makes norovirus so difficult to control. Viruses with membrane coatings are susceptible to alcohol and detergents, but not so norovirus. Norovirus can survive temperatures from freezing to 145 degrees Fahrenheit (about the maximum water temperature in a home dishwasher), soap and mild solutions of bleach. Norovirus can persist on human hands for hours and on solid surfaces and food for days and is also resistant to alcohol-based hand sanitizers.

To make things worse, only a tiny dose of the virus – as few as 10 viral particles – is needed to cause disease. Given that an infected person can excrete many billions of viral particles, it's very difficult to prevent the virus from spreading.

[...] If a group of people is exposed to a strain of norovirus, who gets sick will depend on each person's blood type. But, if the same group of people is exposed to a different strain of norovirus, different people may be resistant or susceptible. In general, those who do not make the H1-antigen and people with B blood type will tend to be resistant, whereas people with A, AB, or O blood types will tend [to] get sick, but the pattern will depend on the specific strain of norovirus.

This difference in susceptibility has an interesting consequence. When an outbreak occurs, for example, on a cruise ship, roughly a third of the people may escape infection. Because they do not know the underlying reason for their resistance, I think spared people engage in magical thinking – for example, "I didn't get sick because I drank a lot of grape juice." Of course, these mythical evasive techniques will not work if the next outbreak is a strain to which the individual is susceptible.

A norovirus infection provokes a robust immune response that eliminates the virus in a few days. However, the response appears to be short-lived. Most studies have found that immunity guarding against reinfection with the same norovirus strain lasts less than six months. Also, infection with one strain of norovirus offers little protection against infection from another. Thus, you can have repeated bouts with norovirus.

The diversity of norovirus strains and the impermanence of the immune response complicates development of an effective vaccine. Currently, clinical trials are testing the effects of vaccines made from the capsid proteins of the two most prevalent norovirus strains.

In general, these experimental vaccines produce good immune responses; the longevity of the immune response is now under study. The next phase of clinical trials will test if the vaccines actually prevent or reduce the symptoms of norovirus infection.


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  • (Score: 0) by Anonymous Coward on Monday January 13 2020, @01:31AM (2 children)

    by Anonymous Coward on Monday January 13 2020, @01:31AM (#942606)

    Same here, when I was a kid, I got the stomach flu a lot and I'm O positive. That's not to say that it's proof that the science is correct, just that I'm not a data point that disproves it.

    Interestingly enough, I've never had the flu, the closest I've ever gotten to the flu was when I had the shot. I got just about every side effect listed on the fact sheet and was sick for nearly an entire week. Since then, I've decided that I won't get another shot as it's just not worth it for me when there are other people that would likely benefit more than I would.

  • (Score: 0) by Anonymous Coward on Monday January 13 2020, @03:43AM

    by Anonymous Coward on Monday January 13 2020, @03:43AM (#942635)

    If you don't get the flu shot you are putting the vulnerable at risk. Have you told your doctor about your choice to do this?

  • (Score: 2) by All Your Lawn Are Belong To Us on Monday January 13 2020, @07:36PM

    by All Your Lawn Are Belong To Us (6553) on Monday January 13 2020, @07:36PM (#942834) Journal

    I think the article was talking about susceptibility, as in who's more likely to get it. Which may help in figuring out how to fight it, and also may provide public health officials with better information in structuring resources to fight it. When it comes to individual cases, though, there is room for 'error' as it isn't deterministic.

    --
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