106 votes
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What's the evidence against SARS-CoV-2 being engineered by humans?

At the moment, there is very little scientific literature about this, but I found two papers that address the problem and are fairly easy to understand. You can find them in the references. Reference ...
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79 votes
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Do beneficial viruses exist? If so, what examples are there?

Do they exist? Yes What are they called? Marilyn Roossinck calls them viral mutualistic symbiotes. She has an excellent review here. What are some examples? My personal favorite is GB-Virus C, or ...
  • 8,721
71 votes

Can the dead be brought back to life by viruses?

You must tell facts from fiction; viruses need living cells to replicate because they do not have the molecular machinery at hand to generate energy and construct building blocks essential to life. So ...
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59 votes
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Are the social-distancing measures implemented against SARS-CoV-2 also suppressing the spread of other viruses?

Yes, this helps as well with other infectious diseases. A good example is the flu, which season was measurably shorter this year than in other years on record. See the figure from the reference 1 for ...
  • 49.4k
55 votes

Virus cannot survive on surface after certain time period, but why and how?

Many important viruses are coated with a lipid envelope and rely on this to enter the host cell. This envelope is fragile - it's similar to a soap bubble - and it can be disrupted in many ways. Lipids ...
  • 3,250
54 votes

How do mutations of viruses lead to drug resistance?

It doesn't. Viruses don't "know" anything. Mutations occur at random. Most of them don't do anything, or have a slight negative effect on the ability of the virus to infect and reproduce. However, ...
53 votes
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How does a Coronavirus "test kit" work?

The CDC has made available online its nCoV test kit. Briefly,the kit contains primers and probes for real-time reverse-transcriptase PCR, as well as instructions for appropriate use and (critically) ...
  • 14.1k
53 votes

Why does vaccine development take so long?

Roni Saiba's answer does a good job of explaining what goes into current vaccine development and why it takes so much effort, but I want to directly address the question of why we can't just grow some ...
  • 3,250
48 votes

Why do some viruses cease being a problem even though no vaccine or cure is found?

Infections spread in a population when the number of new infections caused by an infected person is greater than or equal to 1. If each infected person spreads the virus to less than 1 person, ...
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47 votes
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Is the Common Cold an Immune Overreaction?

Can someone die of the common cold? No. The common cold is a clinical syndrome restricted to upper respiratory tract involvement. By clinical syndrome, I mean it is the constellation of symptoms (...
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43 votes
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Does the genetic sequence of SARS-CoV-2 end with 33 A's?

This is a poly(A) tail, which is a feature found in the majority of eukaryotic RNAs (especially mRNA) and is also not uncommon in RNA viruses (which essentially mimic endogenous mRNA for their own ...
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43 votes
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How many times has SARS-CoV-2 mutated?

This question makes a number of incorrect assumptions and I don't have time to correct them. The short answer is that the virus has mutated probably hundreds of times since it entered humans in late ...
  • 14.1k
40 votes

Are the social-distancing measures implemented against SARS-CoV-2 also suppressing the spread of other viruses?

In addition to Chris' answer above, the effect is even more pronounced in Southern Hemisphere countries where flu season started during the pandemic. The New Zealand lockdown and health response ...
40 votes

Why does vaccine development take so long?

While the existing answers are great and cover a lot of the difficulties in vaccine development, I feel that they fail to address (or at least sufficiently emphasize) the fundamental misconception at ...
39 votes

Killing enveloped viruses with soap

Soap molecules are amphiphilic. This means those molecules have parts which are hydrophilic (water-loving, or "polar") and parts which are hydrophobic (water-avoiding, or "non-polar&...
38 votes
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Why don't we develop immunity against common cold?

Long lasting immunity is obtained by means of the adaptive immune system, and mainly involves the development of antibodies that identify specific parts (epitopes) of the pathogen's proteins. Common ...
  • 1,720
37 votes

Do viruses or bacteria have a flavour?

So I think this is a more conversational kind of question. I will address some misconceptions you have, and I will try to keep it brief, considering the nature and depth of your question. One could ...
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37 votes
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Why don't viruses cause wounds?

A virus does not destroy that many cells before it is exterminated by the immune system or before the host dies. Perhaps even more crucially, viruses typically target a very specific type of cell — ...
  • 3,792
37 votes

Why don't viruses reach broad concentration outdoors in a city like allergens?

2, 4, 5, and 6. 6 being that the UV light (from the sun), fluctuations in temperature, humidity, wind etc mean that the virions are decayed relatively rapidly for most virus species. To address (1): ...
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36 votes
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Can Biologists identify all viruses?

Do physicians/biologists not know all the different types of viruses out there? No, Biologists don't know all the viruses that exist out there. There's a lot! We do know many of the ones infecting ...
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36 votes
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Do viruses or bacteria have a flavour?

As you could imagine, a systematic cataloguing of bacterial or viral flavor profiles would violate a number of biosafety protocols. However, in a laboratory setting, different bacteria definitely have ...
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35 votes
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Are all emerging viral diseases of the past 100 years zoonoses?

To my knowledge, yes. A partial list of recently emerged/emerging viral diseases (I certainly could have missed some), with probable reservoir hosts: Chikungunya* (birds, rodents) coronaviruses (SARS ...
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33 votes
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How did scientists discover HIV?

HIV was identified as an infectious disease through classical epidemiology, and the virus was identified through classical virology. I won't get into the epidemiology, but briefly it went pretty much ...
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32 votes

Why don't we have vaccination against all diseases caused by microbes?

Mainly cost/benefit analysis. Using vaccines has a cost, both in dollars and in risk. That cost may be very low (cheap safe vaccines, like measles vaccine), or may be relatively high (smallpox vaccine ...
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30 votes
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What does vaccine efficacy mean?

Vaccine efficacy Pfizer's target measures for efficacy (see the study on clinicaltrials.gov) seem to be: Confirmed COVID-19 in Phase 2/3 participants without evidence of infection before vaccination ...
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29 votes

Why are more children being hospitalized with Covid-19?

Right now, at least, it's not clear whether anything significant has changed biologically for children with respect to the Delta variant. What is known for certain, however, is that Delta is very ...
  • 6,957
29 votes

Are fully vaccinated people more likely to not get infected at all with COVID-19?

Yes, this is the effect of the vaccine. A reduction of infections of over 88%, a reduction of severe cases and death by 95% and higher. See reference 1 for the details. Data from the ReCoVAM Study ...
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28 votes

Virus cannot survive on surface after certain time period, but why and how?

Ultraviolet (UV) light emitted from the sun has enough energy to break chemical bonds in DNA and RNA. Some frequencies of UV light can cause damage in the DNA in skin cells that can lead to ...
27 votes

Why don't we develop immunity against common cold?

First, I want to note that ddiez has a good answer, but I thought this was good question to have a more expanded answer on immunology and pathogenesis. The First thing we need to establish what is a &...
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27 votes
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Isolation of viruses and Koch's Postulates in connection with terrain theory and claims that viruses don't exist

It is very easy to disprove their claims, but the burden of proof doesn't lie with you, it lies with the person making the claim. If they want to claim that there is a "cell waste product" ...
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