Asymptomatic spread: who
can really spread COVID-19?
https://www.hartgroup.org/asymptomatic-spread/
By Dr John Lee
retired Professor of Pathology
A respiratory virus needs associated symptoms in
order to be clinically relevant.
One year ago, this belief would have been universally accepted by the wider
medical community.
The Health Secretary, addressing the nation on
television on 20 December 2020 stated that ‘If you act like you have the virus,
then that will stop it from spreading to others.’ This messaging is clear in
the many adverts and public health announcements currently circulating.
The response to COVID-19 has been predicated on the assumption that
asymptomatic PCR positive individuals can spread disease. This assumption was
simply accepted as fact and, thus far, has never been adequately demonstrated
in the available scientific evidence.
This single assumption is driving most of the restrictions. It is being
repeated on radio and other advertisements and is causing the populace great
fear and distress. It cannot be left unscrutinised any longer. If there are flaws
in PCR testing regimes that have perpetuated this idea, we must now bring them
to light.
The proportion of people who test positive but have no symptoms ranges from 4%1 to 76%.2 This
is, in large part, a function of how testing has been carried out. If
‘asymptomatic COVID-19’ was a type of presentation of a disease, like a cough,
then you would expect it to occur in the same percentage of the patients no
matter where or when you measured it. The large range here demonstrates that it
is not measuring a phenomenon related to the disease itself.
These are the three situations where someone can be ‘PCR positive’ but
asymptomatic:
1.
Pre-symptomatic –
people who are in the incubation period of real disease and who go on shortly
to develop symptomatic illness. For one to two days these people can transmit
the virus to others and account for a maximum of 7% of spread.3
2.
False Positive test results –
people who test positive but are not really infected, the rate of which is unknown,
but is estimated to be between 0.8% and 4% of all tests carried out.4 The
number increases as Ct cycles are increased. Anything above 25 Ct is now
considered ‘uninfectious’. When carrying out hundreds of thousands of tests,
and including results up to Ct 30 as is the case in the Government surveys, we
are going to inevitably have an enormous amount of false positives. A
respiratory virus needs associated symptoms in order to be clinically relevant.
One year ago, this belief would have been universally accepted by the wider
medical community.
3.
Immunity – people who have the
virus ‘on board’ (detectable) but never develop symptoms. This category used to
be referred to as “immunity” or “healthy people”. This occurs where, even if a
virus is inhaled and present in the respiratory tract, the person is oblivious
and remains completely well, as their immune system deals with the infection
and they never develop symptoms. The evidence these individuals are a
transmission risk is minimal.
Positive PCR is not evidence of infectiousness.
Finding people who test positive but show no symptoms during an outbreak is
often evidence of immunity, not evidence of transmission. Unfortunately, this
has been largely overlooked in the current set of assumptions driving policy.
Evidence of transmission requires that an individual can be shown to be the
source of infection for another person who then developed symptoms of a
disease/illness.
Infectiousness or transmission of a virus requires active infection resulting
in high levels of viral replication and shedding. Symptoms, such as coughing,
are the real drivers of spread.
When the viral replication process is blocked by a healthy immune system, the
virus is neutralised, preventing significant viral replication and shedding. This
happens in approximately half the people exposed to the virus. Their immune
system’s defences effectively ward off COVID-19 before it can take hold and
cause symptomatic disease. It stops it dead in its tracks.
A review of all the published meta-analyses on asymptomatic transmission
reveals that the same few studies have been recycled repeatedly by respectable
institutions.5 On deeper inspection of the published studies
we find that the evidence is of very poor quality. Robust evidence of
asymptomatic spread is lacking and runs counter to all previous understanding
of how respiratory viruses transmit.
The case studies cited as evidence of asymptomatic transmission amount to just
6 individuals who were alleged to have spread COVID-19 to 7 other people. The
studies outlined below are the totality of the worldwide evidence for
asymptomatic spread.
● Two of these case studies, originating from
China, may well have been one patient,6 with the story repeated in separate
publications.7 This was a situation where neither person
involved in transmission had any symptoms. It therefore fails as evidence of
disease spread, which requires the presence of symptoms.
● Two further cases of possible asymptomatic transmission were from Vo in
Italy,8 where
the whole town was tested. 1% of the tests were positive in the absence of
symptoms. The Government’s own estimates for the percentage of tests that give
a false positive result is between 0.8-4.0%9 and as this was a new test, a rate of 1%
would have been very respectable. The alleged result of transmission was again
claimed to cause ‘cases’ with no symptoms. These were likely false positive PCR
test results, and assuming chains of transmission based on the degree of
positivity of a test result is bad science.
● The final two examples were both from studies in Brunei.10 The
evidence is weakened by a poor case definition (any symptom of any severity was
considered real symptomatic COVID-19) and a high probability of false positive
results. The first case was a father who remained asymptomatic but whose wife
briefly had a runny nose and whose baby had a mild cough for one day. In the
second case, a 13 yr old girl with no symptoms was alleged to have spread
COVID-19 to a middle aged woman who had “a mild cough on one day”.11
It is therefore arguable that the asymptomatic
diagnoses last spring were all due to false positive test results. No testing
system is perfect.
Failure to acknowledge this and misinterpretation of positive results in
patients with no symptoms has been hugely damaging.
It would not be unreasonable to state that the current extreme interventions
are entirely based on the assumption of asymptomatic spread of disease, because
otherwise simply requiring the symptomatic and their contacts to isolate would
be sufficient.
Given that asymptomatic spread assumptions drive all of the other non-clinical
interventions (mass-testing of healthy people, mandatory wearing of masks,
social distancing and lockdowns), the evidence here must urgently be
re-evaluated by policymakers.
Endnotes
1.
Follow-up of
asymptomatic patients with SARS-CoV-2 infection
3.
Presymptomatic Transmission of
SARS-CoV-2 — Singapore, January 23–March 16, 2020
4.
Impact of
false-positives and false-negative s in the UK’s COVID-19 RT-PCR testing
programme
5.
Covid: The
woeful case for asymptomatic transmission
6.
Secondary
Transmission of Coronavirus Disease from Presymptomatic Persons, China
7.
Modes of
contact and risk of transmission in COVID-19 among close contacts
8.
Suppression
of a SARS-CoV-2 outbreak in the Italian municipality of Vo
9.
Impact of
false-positives and false-negative s in the UK’s COVID-19 RT-PCR testing
programme
10. Analysis of SARS-CoV-2
Transmission in Different Settings, Brunei
11. Asymptomatic transmission of
SARS-CoV-2 and implications for mass gatherings
