Thread by @DrHugoA

1/ #coronavirus #covid19 for lay friends (as I understand it) - info from various inc
rebelem.com/covid-19-the-n…
emcrit.org/ibcc/COVID19/

Nomenclature: The virus causing this outbreak has been named SARS-CoV-2, the disease it causes is COVID-19

2/ It is part of a family that includes SARS & MERS but also coronaviruses causing milder colds

3/ Pathology & why we're worried:
Revolves around how infectious it is (R0, how many people each case infects), the Case Fatality Ratio (CFR) & the proportion that get critically ill and require intensive care support (e.g. ventilators).

4/ R0 is around ~2.2-3.9 ie each case infects 2-4 others. It's similar to pandemic flu, more than seasonal flu (0.9-2.1) and less than measles (12-18). To get herd immunity 1 – (1/R0) of your population needs to have been infected. For this virus that's ~50-75% of the population.

5/ R0 is a function of both the virus AND human behaviour: better hand hygiene and social distancing measures can lower it (effectively what China, South Korea and Singapore have done).

6/ The CFR is probably <1% but while we know how many have died, we don’t know how many are infected (see diagnosis below). By comparison the CFR for flu is 0.06%.

7/ More worryingly while 81% get no/mild disease, 14% get severe disease (eg low oxygen levels) and 5% critical disease requiring intensive care support (in ~44,500 Chinese cases) jamanetwork.com/journals/jama/…

8/ We have ~4,000 intensive care beds in the UK (trying to increase), mostly occupied for other serious illnesses. These will rapidly get filled if we are unable to slow the spread and without intensive care support critically ill patients will die. This is what worries doctors.

9/ Symptoms:
Several cohorts of cases identify fever (in 43-98% in the cohorts studied) and cough (68-82%) as most common, but can have cold symptoms, muscle aches, breathlessness, or even diarrhoea and nausea. This makes it very hard to distinguish from other illnesses.

10/ Diagnosis:
The ‘test’ for SARS-CoV-2 is a nose +/- throat swab that looks for the virus (using technology called PCR). It is a new test limited to accredited labs, with hospital labs rapidly becoming accredited, but partly explains why results are slower than for flu.

11/ The test has a sensitivity of ~75%. This means ~25% of people with a negative test result may have the virus (one study retested 64 patients with suspected virus & a negative test found it was positive in 15/64). So even if we could, testing everyone would not be that helpful

12/ Practically speaking, follow the latest NHS guidance on 111 online. Do NOT go to your GP or A&E unless instructed as you risk infecting others and having the place shut down for a deep clean.

13/ In the cohorts of infected patients studied, blood tests are usually in the normal range, with a tendency for some white cells (lymphocytes) to be on the low side. So again not very helpful.

14/ Chest X-rays are useful for identifying those with signs of potentially severe respiratory disease that may need ventilatory support. The additional information from a CT scan doesn't change management & leave the CT scanner requiring a deep clean so generally isn't pursued.

15/ Prevention & Treatment:
1) HYGIENE. The virus has a feeble fatty envelope that is vulnerable to soap, alcohol & bleach. It can persist on surfaces for days. Cover when you cough/sneeze, try not to touch your eyes/nose/mouth where it enters the body, & wash your hands often.

16/
(2) Self isolate if you have either a new cough (dry or productive) OR fever >37.8 as per current guidance. This will prevent spread and give our intensive care the ability to keep up.

17/
(3) Treatment is supportive; there is no drug or therapy (yet) that treats the virus or its complications. Mild cases can be managed at home, severe cases get organ support but e.g. no antibiotics (unless a superimposed bacterial infection suspected).

18/
(4) The future. Vaccines are likely 12-18m away. Drug trials are ongoing, some results out soon. My guess is antivirals will probably need to be given early (like tamiflu/oseltamivir) & as discussed it is hard to spot those who have the virus.

19/ We need drugs that reduce the severity of illness to take the strain off intensive care… watch this space.

20/ Misc: SARS-CoV-2 binds the ACE2 receptor on cells lining the respiratory tract (& others). It's hypothesised that ACE2 is expressed at low levels in kids & increased in those on certain drugs (blood pressure drugs ACE inhibitors & Angiotensin Receptor Blockers, ibuprofen) BUT

21/ We don’t have hard evidence of this. So you might want to go for paracetamol over ibuprofen, although there isn’t much to support this currently.

22/ Asthma. Standard coronavirus, like any respiratory virus, can make asthma worse. Most now think treatment for everyone with asthma should include an inhaled corticosteroid, even if only taken as needed, to dampen the inflammation driving the symptoms (not just a blue inhaler)

23/ Asthma cont. If your asthma symptoms get worse or you get a cold, increase the number of puffs you take of your inhaled corticosteroid (or combination inhaler) +/- seek help. This is in line with guidance asthma.org.uk/advice/trigger…

@threadreaderapp unroll