Since the first outbreak of COVID-19 in 2019, researchers and scientists have been working to better understand and find optimum treatments for SARS-CoV-2, including COVID-19 vaccines.
 
COVID-19 vaccines have proven to be safe, effective, and life-saving. All COVID-19 vaccines approved by WHO for emergency use have been subject to clinical trials to test their safety, quality, and efficacy.  Vaccinations not only limit the risk of infection   but also reduce the severity of COVID-19 symptoms.
 
In other words, COVID-19 vaccines are a critical tool for controlling the ongoing global pandemic. However, vaccines do not provide full protection.  Although the risk of vaccinated people becoming infected with SARS-CoV-2 is low (a scenario often called “breakthrough infection”), it can still happen. So as well as getting vaccinated, it is still important to persist with other measures to fight the pandemic.
 
As the Delta variant is spreading, some vaccinated people are testing positive for COVID-19 in the United States, as reported by the Wall Street Journal. Nationwide, about 97% of people hospitalized with COVID-19 are unvaccinated (as stated by CDC Director Dr. Rochelle Walensky), people with so-called breakthrough infections of the delta variant can spread the virus to others just as readily as unvaccinated people.
 
In this article, we will investigate this scenario and share further information about the testing options currently available.
  Positive COVID-19 Test Results After Vaccination
 
Covid-19 vaccines are saving lives.  In a recent study tracking more than 200,000 people in the UK, nearly every single participant had developed antibodies against COVID-19 within two weeks after their second dose. 
 
Despite initial worries regarding a potential lower effectiveness of current vaccines against the Delta variant, the AstraZeneca and the Pfizer-BioNTech jabs have been shown to reduce hospitalization rates by 92-96%. Yet, doubts and concerns related to the side effects and consequences of vaccination are spreading.
 
One of the concerns is whether getting a COVID-19 vaccine will result in a positive result   for COVID-19 on a viral test, such as the PCR or antigen tests. None of the authorized and recommended COVID-19 vaccines cause individuals to test positive on viral tests, which are used to identify a current infection.
 
In the scenario where a person’s body develops an immune response to vaccination, there is the possibility of testing positive on some antibody tests. Antibody tests indicate the presence of antibody due to a previous infection or vaccination and that the individual developed some level of protection against the virus. It takes approximately 1 to 3 weeks following the infection for our body to make antibodies. Thus, if tests are carried out during that time, antibody testing may not identify the virus presence.
 
The COVID-19 Testing Landscape
 
Despite large-scale vaccination campaigns, testing is still a priority worldwide. The COVID-19 tests landscape is segmented mainly into three different types: PCR molecular tests, antigen tests, and antibody tests.
 
PCR and antigen tests are regarded as diagnostic tests. Both tests can detect active COVID-19 infections, and samples are generally collected with a nasal or throat swab.
 
The turnaround time for molecular tests is over two hours.  Once the specimen is obtained, the RNA is extracted and transcribed into DNA. Then, the DNA is amplified by PCR with COVID-19 specific primers in the laboratory.
 
By contrast, the antigen test sample is processed with reagents to disrupt the particle of the virus and expose the viral proteins. Antigen tests are often called "rapid tests" because of the short turnaround time (15-20 minutes).
 
Antibody test, or serological testing is employed to confirm the presence of past COVID-19 infections. In particular, antibody tests search for specific antibodies in patients' immune systems. Such antibodies develop after days or weeks from the infection. The presence of IgM and IgG antibodies in the specimen indicate prior COVID-19 infection. Antibody test samples are obtained from the individuals' blood or serum. The average turnaround time for serological tests is approximately 15-20 minutes.
 
Considering the COVID-19 test application scenarios, antigen and antibody rapid tests are employed for initial screening. These types of tests can improve the detection rate in individuals that are either asymptomatic or showing mild COVID-19 symptoms. 
 
Real-time PCR is considered the gold standard in COVID-19 diagnostic testing. PCR testing is considered one of the most reliable testing options. However, molecular testing is not suitable to be implemented during emergencies because of its longer turnaround time.

Conclusion
 
Vaccination is an essential tool to help stop the pandemic. COVID-19 vaccines prevent severe illness, hospitalizations, and death. It is imperative to keep running tests to monitor and contain the spread of the SARS-CoV-2. With the Delta variant, testing is even more important, especially for unvaccinated individuals.
 
However, not all tests are created equal. The three main types of COVID-19 test - PCR molecular tests, antigen tests, and antibody tests - all work in different ways to diagnose infection or assess immunity.
 
Wondfo has been researching, developing, and innovating its COVID-19 diagnostic products since January 2020. The COVID-19 prevention and control start from facilitating the early detection, early reporting, early quarantine, and early treatment of the disease and its variants.
Continuous innovation is increasingly essential for an effective response to and recovery  from the COVID‑19 pandemic. Wondfo strives for excellence both in the constant improvement of its POCT products and in the advancement of research. Over 700 top-notch researchers periodically break through the limits of knowledge and research in the POCT and healthcare industries to improve the lives of people worldwide.
 
Learn more about the Wondfo COVID-19 testing solutions, Click here.