What does my pooled result mean?
Below are guidelines set forth by DESE and DPH:
What if a pool comes back with an “Inconclusive” result?
An Inconclusive result means that there was an extremely small amount of virus detected by one of the probes at the laboratory, but not enough to consider the pool positive. The Department of Public Health considers these results to most likely be false positives or to be detecting trace amounts of the virus that are extremely unlikely to be spread. For this reason, there is no need to immediately re-pool the individuals in an Inconclusive pool, or to give them follow up tests, provided that other mitigation measures are carefully followed. While it is extremely unlikely that any individual in an Inconclusive pool would be able to spread the virus, schools are free to utilize follow up tests in this situation if they desire.
What if a pool comes back with an “Invalid” result?
An “Invalid” result could mean several different things, ranging from collection errors (e.g. swabs inserted upside-down) to a one-time error at the laboratory. Because of this range of possibilities, DPH recommends re-testing as soon as possible - either by re-pooling immediately or by follow up testing the members of the pool individually, according to what is preferable or more viable for your school. As opposed to an “Inconclusive” result, please do not wait until the next week to re-pool.
What if I can’t conduct follow up testing on every member of a Positive pool?
In the event that not all members of a positive pool are able to receive follow up BinaxNOW tests (e.g. some are on vacation or otherwise absent), schools should proceed with normal follow up testing protocol with the members of the positive pool that are present. If follow up testing with the BinaxNOW does not identify a positive from among the pool members available, all available members of that pool must be re-tested with either a second BinaxNOW or individual PCR tests. As in other cases, it is not necessary to quarantine/isolate until an individual has received a positive individual test result.
Members of a positive pool who are not immediately available for follow up testing with the rest of their pool should receive follow up testing per normal protocol as soon as it is possible to do so.