107

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 1 is probably the most interesting and is the basis for this answer. Edit: It is also interesting to read reference 2 on the origin of SARS-CoV-2; the article ...


59

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 comparision: Reference 2 shows that this is also true for other respiratory diseases (figure 2): This shows very well that the isolation measures and the ...


54

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) controls and guidelines to avoid false positives and negatives. Kits from different countries may use slightly different primers and probes, though since they ...


50

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, eventually no one will be infected, without a need for any sort of cure. Of course, the longer a deadly infectious disease spreads in a population, the more people ...


43

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 2019. The lower figure on the NextStrain.org ncov page, "Diversity", shows the known mutations that have been identified so far. As I look at it now, there are ...


42

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 replication). As with mRNA, this poly(A) tail in coronaviruses is bound by poly(A) binding protein in the cytoplasm [1], which is involved in translation ...


40

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 dramatically lowered the prevalence of reported flu-like symptoms. Reference: Flu Tracking reports - New Zealand – week ending 31-May-2020


25

There are actually 3+ types of test kits widely used to diagnose diseases caused by viruses. We can check for the nucleic acid of the virus, the antigen of the virus that would cause an immune response or the antibody produced during the immune response of the patient. Since we've already got the whole sequence of the nCoV, the test kits normally used this ...


24

It is hypothesized that exposure to and recovery from SARS-CoV-2 (as with other coronaviruses in humans) would generally result in short-term immunity to this strain, but we do not yet have data on this: However, according to Dr Stephen Gluckman, an infectious diseases physician at Penn Medicine and the medical director of Penn Global Medicine, who spoke to ...


22

2019-nCoV is a virus that originated from the bat (at least this is the current hypothesis). It shows 96% squence similarity to the BatCoV RaTG13 sequence (see reference 1), showing its origin. It still is 87,99% identical to the "Bat SARS-like coronavirus", which explains the hit you found and is not unexpected, as these viruses are very closely related (...


22

Because "any" Coronavirus is so dangerous, much research have been done on viruses with similar properties. They are called "surrogates". Because nCoV is new, we don't have any studies, so we need to estimate it's behavior from previously studied similar viruses. Here: RH = Relative Humidity. Tr = Room Temperature TGEV = Transmissible Gastroenteritis (...


22

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 Confirmed COVID-19 in Phase 2/3 participants with and without evidence of infection before vaccination From Pfizer's study plan (VE = vaccine efficacy): VE ...


21

If you need more [counter]evidence, there's a newer paper "The proximal origin of SARS-CoV-2" by Andersen et al. (March, 17) that touches on the same topic. The paper brings up two reasons why SARS-CoV-2 is not "made in a lab". The first is the (relative) [in]efficiency of its spike protein; the second is somewhat more complex to explain ...


21

Does it really contain a capsid? Yes. Coronaviruses have a capsid, but it's not reminiscent of the polygonal (icosahedral) capsid depicted in the Research Gate picture you referenced. Icosahedral capsids form a sort of shell around the viral genome, where helical capsids actually bind the viral nucleic acids, holding them in a more rigid shape. Is it ...


17

While the data are much too sparse and noisy to give an answer about what is happening to COVID-19's virulence (the technical term for the "deadliness" of an infectious disease), or to forecast what will happen to its virulence in the future, there are indeed theoretical reasons that one might expect the virulence to decline in the future. There is an ...


17

A partial answer, to the question of how the virus might spread to animals I found several references The HongKong dogs, the New York tiger, the Netherlands mink farm and the French cat have been sequenced and can be seen on nextstrain. Note the low amount of mutations in each case, which is intriguing because we expect for example that different ACE2 genes ...


17

Bryan Krause's answer addresses the reasons pertinent to SARS and MERS. If you meant those two as examples but are interested in the title question more generally, I can note an additional mechanism. This is herd immunity, which fits the bill in that it can occur when "no vaccine or cure is found" and when it is neither the case that "all people who had ...


16

It's common for the reservoir host of a zoonotic virus to be tolerant of it. MERS coronavirus appears to cause mild or no disease in dromedary camels ( source ), but kills about 35% of confirmed infected humans. ( CDC ) Sin Nombre hantavirus seems to be mild in the deer mice that spread it, despite ~36% fatality rate in humans. ( source ) Mosquitoes are ...


14

We probably won't really know for certain until we have time to gather more data from survivors. However, infection with existing coronaviruses (including SARS-CoV, genetically very similar to the COVID-19 virus SARS-CoV-2; ref. https://www.nature.com/articles/s41564-020-0695-z) suggests that those who are infected and survive may develop temporary immunity (...


13

There are multiple challenges presented, and many of those are not limited to coronavirus vaccine. As mentioned above, it just takes time. Before a vaccine can be used in patients, clinical trials must be performed to validate the safety and efficiency of the vaccine candidate. A Clinical trial includes three phases, which again, just takes time. But to ...


12

Electron micrographs of negative-stained 2019-nCoV particles were generally spherical with some pleomorphism (Figure 3). Diameter varied from about 60 to 140 nm. Virus particles had quite distinctive spikes, about 9 to 12 nm, and gave virions the appearance of a solar corona. --A Novel Coronavirus from Patients with Pneumonia in China, 2019 Figure 3 from ...


12

In the reference genome browser, it seems you are looking at the first Coding Sequence (CDS) line, YP_009724389.1, which shows the translation to LNRV...: If you look lower down, you'll see a line for CDS YP_009725295.1, which shows translation to LNGF... as you expected. So, these are two different interpretations of possible translations for this area of ...


11

There are several proposed tests for 2019-2020 novel coronavirus responsible for the Wuhan outbreak. The main techniques these are based on are: PCR or qPCR targeted amplification CRISPR-Cas9 genome editing PCR-based tests are the current standard for diagnosis of viral infections (as these are faster than protein staining and can be made widely available ...


11

The preponderance of links between bat and human pathogens has led to a debate about whether bats disproportionately contribute to emerging viral infections crossing the species barrier into humans (26–30). Given the diversity of the Chiroptera order (Figure ​(Figure1),1), we may simply see more bat viruses because there are so many (>1,300) species of bats (...


11

The information you show is meaningless unless it is also accompanied by the number of tests performed. If the CDC tested 2 people and got two positive results, that doesn't tell us anything at all about the actual rate of infection. And, indeed, the CDC has been testing a shockingly low number of cases: ‡ Data during this period are incomplete because of ...


10

Short answer: Although there are some reports on this, it is pretty unlikely. It is more likely that patients where released too early from hospital, developed further symptoms later on and got worse, was re-hospitalized, tested again for SARS-CoV2, which was positive and counted as re-infected. Another possibility is that a false negative test happened, ...


10

I found an answer to this mystery in the literature, but it is a somewhat tentative explanation from a relatively recent (2012) paper by Yang et al. In a nutshell, [respiratory] viruses do worse in small droplets compared to large/unconstrained ones. Even being "totally" dry is apparently somewhat better for them than being trapped in a small ...


10

Update -- In the time since this question was asked, two relevant articles have been published, one in Nature Reviews Immunology and one in medRxiv (note: medRxiv is a preprint server and is therefore not peer reiewed). Scully, E.P., Haverfield, J., Ursin, R.L. et al. Considering how biological sex impacts immune responses and COVID-19 outcomes. Nat Rev ...


9

It's been tentatively proposed that bats are often unusually able to tolerate long-term infection with a wide range of viruses (though this hasn't been formally shown to be true). A specific cause for this (possible) phenomenon isn't known, but many possible explanations have been put forward. It's likely that if it's true, there's no single cause but rather ...


9

I think you're talking (setting aside false-positive/low-specificity testing problems for the moment) about the difference between infection fatality ratio (IFR, fraction of infected people who die from disease) and the case fatality ratio (CFR, fraction of clinically defined "cases" who die from disease). The difference between these two depends completely, ...


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