I rate this fact-check as 'Mostly False'. And 'fact-checkers' as biased as their mainstream media, and Big Tech masters.

Elon Musk took four rapid antigen Covid-19 tests. He got two positive results, and two negative results. He considered himself asymptomatic, but admitted he had 'common cold' symptems. He tweeted that there was something 'bogus' going on.

Claim:
"Something extremely bogus is going on. Was tested for COVID four times today. Two tests came back negative, two came back positive. Same machine, same test, same nurse."

The Twitter fact-checkers flagged the tweet as 'Mostly False' here: https:// www.newswise.com /factcheck/ elon-musk-s-clai m-that-covid-te sting-is-bogus- is-not-accurate / ?article_id=7419 19

1. The 'fact-checkers' didn't disprove Elon Musk claim that 'somethinh 'bogus' was going on with the rapid (antigen) Covid-19 test.

They didn't disprove the fact he had 4 sample tests using approved testing kits administered by the same skilled person in the same way. Of this 4 tests, two returned a positive result, and two a negative result.

Musk's claimed was not disproved and cannot be rated as 'Mostly False', it should be rated as TRUE.

2. Instead the 'fact-checkers' did a 'switch' by simply saying the antigen testing (testing for antibodies), is not as accurate as real-time polymerase chain reaction, (RT-PCR) testing. But the FDA specifically don't advise not to accept positive rapid antigen test results.

In fact the FDA say, (as shown by the fact-checkers):

'Positive results are usually highly accurate, but false positives can happen, especially in areas where very few people have the virus. Negative results may need to be confirmed with a molecular test.'

The FDA say positive results are highly accurate. They only say negative results may need to be confirmed with a molecular test.

3. Contrary to the 'fact-checkers' claims, RT-PCR tests are known for false positives. In fact. 29 September Lancet paper titled, 'False-positive COVID-19 results: hidden problems and costs', provided this statement.

'To summarise, false-positive COVID-19 swab test results might be increasingly likely in the current epidemiological climate in the UK, with substantial consequences at the personal, health system, and societal levels (panel).'

4. There are plenty of examples of proven false positive tests from RT-PCR Covid-19 tests. In Scotland for example.

'When seven staff at a Scottish football club tested positive for coronavirus, alarm bells went off. But really alarming was when six of those results turned out to be wrong. Such inaccurate tests are exaggerating the problem.'

'So, even if the test is very accurate indeed, we could easily end up with four positive tests from people who really do have the virus and 10 false positives from people who don't.'
https:// www.msn.com/ en-in/ entertainment/ other/ due-to-faulty-rt -pcr-kit-chiran jeevi-tested-co vid-19-positive -now-clarifies- result-was-fals e/ar-BB1aYUpY

And here: This research paper published in May, 'False positives in reverse transcription PCR testing for SARS-CoV-2'

'Findings: Review of external quality assessments revealed false positive rates of 0-16.7%, with an interquartile range of 0.8-4.0%. Such rates would have large impacts on test data when prevalence is low. Inclusion of such rates significantly alters four published analyses of population prevalence and asymptomatic ratio. Interpretation: The high false discovery rate that results, when prevalence is low, from false positive rates typical of RT-PCR assays of RNA viruses raises questions about the usefulness of mass testing; and indicates that across a broad range of likely prevalences, positive test results are more likely to be wrong than are negative results, contrary to public health advice about SARS-CoV-2 testing.'
https:// www.researchgate .net/ publication/ 341091306_False_ positives_in_re verse_transcrip tion_PCR_testin g_for_SARS-CoV- 2

And here we have from the Centre of Evidenced Based medicine a research paper asking 'PCR positives: what do they mean?' September 17, 2020.

The researchers concluded there is no correlation between RT-PCR positive infection 'cases' , and Covid-19 deaths. Highly suggesting there are a large number of false positive RT-PCR test results, and they show research papers which explain why this happens.
https:// www.cebm.net/ covid-19/ pcr-positives-wh at-do-they-mean /

I could go on, but the point should be clear, Facebook and other 'fact-checkers' get the result which fits their desired narrative, not the facts. They are simply part of the obvious left wing bias of most mainstream media and Big Tech's social media and search engines, as much of the material I have presented does not appear in the first ten or more search results. Very few people go past the first 5 results.