We need your help now
Support from readers like you keeps The Journal open.
You are visiting us because we have something you value. Independent, unbiased news that tells the truth. Advertising revenue goes some way to support our mission, but this year it has not been enough.
If you've seen value in our reporting, please contribute what you can, so we can continue to produce accurate and meaningful journalism. For everyone who needs it.
Sign in. It’s quick, free and it’s up to you.
An account is an optional way to support the work we do. Find out more.
By continuing, you are indicating that you accept our Terms of Service and Privacy Policy.
A CLAIM THAT a person with a cold or flu will test positive for Covid-19 has surfaced in Ireland in recent days after starting in the US.
The claim, which has appeared in several forms on social media, centres on an argument that conflates antibody testing for previous Covid-19 infections with viral testing for an existing case of Covid-19.
The claim originated in the US based on screenshots from the Center for Disease Control and Prevention (CDC) which said that antibody testing for Covid-19 could return a positive result if the test detected antibodies for a cold.
The CDC statement has been used as the basis for claims on social media that tests for current Covid-19 cases will return a positive if the person tested has the cold or flu, or has ever received a vaccine for a cold or flu. There is no vaccine for a cold, despite what these claims say.
The claim has appeared on social media in Ireland in recent days.
One Ireland-based Facebook page that shared the claim wrote that “coronavirus testing can also be common cold or flu virus if you ever had the cold and flu jab you will test positive for covid 19”.
The post has been viewed 33,000 times in six days and attracted 183 shares.
The claim was spread in the United States on multiple platforms, including from a website called Intellihub.com, which wrote “Shocker: CDC admits Covid-19 ‘positive result’ just means you’ve previously contracted the ‘common cold’”.
Another Facebook post in Ireland that shares a screenshot of the article’s headline has been viewed 19,000 times in six days and includes the caption: “The government is trying to crash the economy over the common cold.”
The Evidence
The statement from the CDC relates to antibody testing for past infection with Covid-19, rather than viral testing for current cases of the virus, which is a completely different thing.
Viral tests are used to identify current cases of Covid-19 by using samples from the respiratory system. In Ireland, viral tests are carried out by swabbing the inside of the nose and the back of the throat.
Antibody tests, however, check the blood of the person being tested for antibodies that fight against Covid-19, which can indicate that a person has previously had a case of Covid-19 which their body sought to protect itself against by producing those antibodies.
It can take one to three weeks for a body to make antibodies after infection.
Viral tests will only pick up cases of Covid-19, not colds or flu.
Speaking to TheJournal.ie, lecturer in immunology and host-microbe interactions at the Department of Biological Sciences at the University of Limerick, Dr Elizabeth J Ryan, said that viral tests for current cases of Covid-19 are “very specific” for material that is “only expressed by the Covid-19 virus”.
“Having a cold or flu won’t change that,” Dr Ryan said.
Similarly, Professor Kingston Mills, a professor of experimental immunology in Trinity’s School of Biochemistry and Immunology, told TheJournal.ie that the viral test for current Covid-19 cases is “very, very specific”.
The test is based on material that is unique to the virus, Professor Mills said, so it’s “not going to pick up influenza or common cold virus”.
The page on the CDC website that gives details on tests for past infection was last updated on 30 June and says a “positive test result shows you may have antibodies from an infection with the virus that causes Covid-19”.
“However, there is a chance a positive result means that you have antibodies from an infection with a virus from the same family of viruses (called coronaviruses), such as the one that causes the common cold,” the CDC statement says.
The CDC is warning here that an antibody test – a test for past infection with Covid-19 – could have the potential to return a false positive result for Covid-19 if the person tested has created antibodies for another infection caused by a different type of coronavirus, like one that can cause a cold.
Dr Ryan said that some antibody tests which are not properly validated are not specific enough for the virus they are testing for and can pick up other antibodies instead, giving a “false positive test”.
Validated tests are ones which have been rigorously tested in a laboratory environment, such as by verifying the test through samples of the virus that have already tested positive.
The World Health Organization has warned against using rapid tests that have not been validated, except in a research setting.
“Coronavirus, if you are infected with the virus, will be in your system for a couple of weeks. Your immune system will clear this, and in the process of clearing it, you will mount an antibody response – an immune response,” Dr Ryan said.
“Most people will produce antibodies when they’re infected. The antibody test is looking for those antibodies.
The antibody tests are not all equal. Some tests from different manufacturers have been properly validated, and those properly validated tests will test the specific antibody to Covid-19. Other coronaviruses [than Covid-19] exist and can cause the common cold. We’ve all had them, probably, at some point, so we will all have antibodies in our system to those viruses.
“Tests that have been properly validated and gone through proper regulatory channels will account for that and we will look for that when we’re developing those tests, to make sure that there is no cross-reactivity between the virus that causes Covid-19 and other coronaviruses.
“You will only have antibodies to Covid-19 if you have had the virus,” she said.
Some private laboratories in Ireland are offering antibody testing for Covid-19 at a charge, but antibody testing for Covid-19 is not being carried out widely among the public in Ireland at present.
The HSE and the UCD National Virus Reference Laboratory are currently using antibody testing for a study looking to estimate the number of people in the country who have been infected with Covid-19.
Antibody tests are not currently counted towards daily reporting of the number of Covid-19 cases in Ireland. The number of cases is counted using the results of polymerase chain reaction (PCR) tests – that is, tests that identify an existing infection with Covid-19.
Professor Mills also said that 10-minute or strip tests for antibody testing which have not been properly validated could falsely return a positive result due to colds, but that properly validated tests for antibodies are specific to Covid-19.
The HSE antibody study uses properly validated tests. Participants have a blood test carried out in a local centre with a nurse, and the blood sample is sent to the National Virus Reference Laboratory in UCD, where it is tested for antibodies.
Although people in Ireland can obtain a flu vaccine, there is no vaccine against the common cold.
Colds can be causes by several different types of viruses, including rhinoviruses, adenoviruses, and coronaviruses.
The Verdict
Antibody testing and viral testing are carried out differently and look for different things.
Antibody testing identifies past infection with a virus by looking for antibodies in blood that the body has produced against the virus. Viral testing looks for an existing case of the virus, and is done with a sample from the respiratory system – that is, a swab to the throat and/or nose.
The statement from the CDC said that an antibody test – a test for a past infection – for Covid-19 could pick up antibodies for other types of coronaviruses, such as a cold.
The CDC’s statement has been used to spread a claim that tests for Covid-19 – including tests for existing cases – will return a positive result if the person has a cold or flu, or if they have ever had a vaccine against the cold or flu.
Although there is a chance that an antibody test that is not properly validated can return a false positive due to a cold that was caused by a coronavirus, a test that is properly validated will only identify antibodies that the body has produced against Covid-19.
The flu is caused by a different virus entirely, and cannot cause a false positive result.
An antibody test will not return a positive due to a person previously being vaccinated against the flu. Additionally, a vaccine against the common cold does not exist.
Testing for an existing case of Covid-19 will not return a positive result due to a cold or flu.
As a result, we rate the claim that a common cold can cause a positive result for a Covid-19 test: FALSE.
As per our verdict guide, this means: The claim is inaccurate.
TheJournal.ie’s FactCheck is a signatory to the International Fact-Checking Network’s Code of Principles. You can read it here. For information on how FactCheck works, what the verdicts mean, and how you can take part, check out our Reader’s Guide here. You can read about the team of editors and reporters who work on the factchecks here.
To embed this post, copy the code below on your site
Use precise geolocation data. Actively scan device characteristics for identification. Store and/or access information on a device. Personalised advertising and content, advertising and content measurement, audience research and services development.
These cookies are necessary for the website to function and cannot be switched off in our systems. They are usually only set in response to actions made by you which amount to a request for services, such as setting your privacy preferences, logging in or filling in forms. You can set your browser to block or alert you about these cookies, but some parts of the site will not then work.
These cookies may be set through our site by our advertising partners. They may be used by those companies to build a profile of your interests and show you relevant adverts on other sites. They do not store directly personal information, but are based on uniquely identifying your browser and internet device. If you do not allow these cookies, you will experience less targeted advertising.
These cookies enable the website to provide enhanced functionality and personalisation. They may be set by us or by third party providers whose services we have added to our pages. If you do not allow these cookies then these services may not function properly.
These cookies allow us to count visits and traffic sources so we can measure and improve the performance of our site. They help us to know which pages are the most and least popular and see how visitors move around the site. All information these cookies collect is aggregated and therefore anonymous. If you do not allow these cookies we will not be able to monitor our performance.
Cookies, device or similar online identifiers (e.g. login-based identifiers, randomly assigned identifiers, network based identifiers) together with other information (e.g. browser type and information, language, screen size, supported technologies etc.) can be stored or read on your device to recognise it each time it connects to an app or to a website, for one or several of the purposes presented here.
Advertising presented to you on this service can be based on limited data, such as the website or app you are using, your non-precise location, your device type or which content you are (or have been) interacting with (for example, to limit the number of times an ad is presented to you).
Information about your activity on this service (such as forms you submit, content you look at) can be stored and combined with other information about you (for example, information from your previous activity on this service and other websites or apps) or similar users. This is then used to build or improve a profile about you (that might include possible interests and personal aspects). Your profile can be used (also later) to present advertising that appears more relevant based on your possible interests by this and other entities.
Advertising presented to you on this service can be based on your advertising profiles, which can reflect your activity on this service or other websites or apps (like the forms you submit, content you look at), possible interests and personal aspects.
Information about your activity on this service (for instance, forms you submit, non-advertising content you look at) can be stored and combined with other information about you (such as your previous activity on this service or other websites or apps) or similar users. This is then used to build or improve a profile about you (which might for example include possible interests and personal aspects). Your profile can be used (also later) to present content that appears more relevant based on your possible interests, such as by adapting the order in which content is shown to you, so that it is even easier for you to find content that matches your interests.
Content presented to you on this service can be based on your content personalisation profiles, which can reflect your activity on this or other services (for instance, the forms you submit, content you look at), possible interests and personal aspects. This can for example be used to adapt the order in which content is shown to you, so that it is even easier for you to find (non-advertising) content that matches your interests.
Information regarding which advertising is presented to you and how you interact with it can be used to determine how well an advert has worked for you or other users and whether the goals of the advertising were reached. For instance, whether you saw an ad, whether you clicked on it, whether it led you to buy a product or visit a website, etc. This is very helpful to understand the relevance of advertising campaigns.
Information regarding which content is presented to you and how you interact with it can be used to determine whether the (non-advertising) content e.g. reached its intended audience and matched your interests. For instance, whether you read an article, watch a video, listen to a podcast or look at a product description, how long you spent on this service and the web pages you visit etc. This is very helpful to understand the relevance of (non-advertising) content that is shown to you.
Reports can be generated based on the combination of data sets (like user profiles, statistics, market research, analytics data) regarding your interactions and those of other users with advertising or (non-advertising) content to identify common characteristics (for instance, to determine which target audiences are more receptive to an ad campaign or to certain contents).
Information about your activity on this service, such as your interaction with ads or content, can be very helpful to improve products and services and to build new products and services based on user interactions, the type of audience, etc. This specific purpose does not include the development or improvement of user profiles and identifiers.
Content presented to you on this service can be based on limited data, such as the website or app you are using, your non-precise location, your device type, or which content you are (or have been) interacting with (for example, to limit the number of times a video or an article is presented to you).
With your acceptance, your precise location (within a radius of less than 500 metres) may be used in support of the purposes explained in this notice.
With your acceptance, certain characteristics specific to your device might be requested and used to distinguish it from other devices (such as the installed fonts or plugins, the resolution of your screen) in support of the purposes explained in this notice.
Your data can be used to monitor for and prevent unusual and possibly fraudulent activity (for example, regarding advertising, ad clicks by bots), and ensure systems and processes work properly and securely. It can also be used to correct any problems you, the publisher or the advertiser may encounter in the delivery of content and ads and in your interaction with them.
Certain information (like an IP address or device capabilities) is used to ensure the technical compatibility of the content or advertising, and to facilitate the transmission of the content or ad to your device.
Information about your activity on this service may be matched and combined with other information relating to you and originating from various sources (for instance your activity on a separate online service, your use of a loyalty card in-store, or your answers to a survey), in support of the purposes explained in this notice.
In support of the purposes explained in this notice, your device might be considered as likely linked to other devices that belong to you or your household (for instance because you are logged in to the same service on both your phone and your computer, or because you may use the same Internet connection on both devices).
Your device might be distinguished from other devices based on information it automatically sends when accessing the Internet (for instance, the IP address of your Internet connection or the type of browser you are using) in support of the purposes exposed in this notice.
The choices you make regarding the purposes and entities listed in this notice are saved and made available to those entities in the form of digital signals (such as a string of characters). This is necessary in order to enable both this service and those entities to respect such choices.
have your say