New booster before antigen test

[odysee]

We were waiting for the new boosters before our Transatlantic (have already 2 vaccinations and 1 booster with old Pfizer version).

Now rollout of newer kind of vaccination is becoming delayed here and I fear we might only get it 1 week or so before having to test for TA.  Not sure which make we will finally get.

 

Does anyone have experience with new vaccinations and/or can confirm that it will not mess up antigen test so soon after (ie showing positive) ?

thanks in advance

[mfs2k]

Yes actually. 
I got the new booster on Thursday and got an antigen and PCR test on Monday. 
Both were negative. 

I can’t speak for the world. Just my own results. 

[prmssk]

There is no live virus in the vaccines that would affect an antigen or PCR test.

[Denny01]

Just got the new booster prior to our TA. Asked the pharmacist of any issues w tests. Response was None. Going to mask up in crowds till cruise

 

den

[cruisestitch]

With no live virus in the booster it can’t show up as positive on your tests.

[cangelmd]

I looked this up, because I thought wait a minute, why couldn’t there be a very rare false positive. The answer is theoretically it could happen, but practically it is impossible to have a false positive antigen test from the mRNA vaccines.

 

mRNA vaccines introduce mRNA that encodes for viral spike protein (which is an antigen). The spike protein is produced, and the immune system reacts to it, cells die (which is why some of us get really sore arms from the shots) and an immune response occurs. Most rapid antigen tests in the US and Europe test for a nucleocapsid antigen, so the test is looking for a different protein that should only be seen in natural infection. The second reason that a false positive from vaccination would likely never occur is that you get the shot in your arm, and the immune response is localized. The test is done on a nasal swab. It is highly unlikely that enough spike protein from the shot woukd ever end up in your nasal secretions - the Ag tests aren’t that sensitive.

[odysee]

Thanks a lot - very reassuring as the gap between the planned booster and the required antigen test decreases continuously.  We might even still have to go last minute for a 2nd booster with the old vaccine 🫣

[hazelk]

I was concerned over this too, we get our booster and flu jags on Saturday 8th October, antigen test is on Tuesday 11th in Barcelona a day before our transatlantic cruise.  I called my doctor who assured me the booster would have no affect on my antigen test. 

[Jim_Iain]

I also asked my doctor and he said there should be no problem as the vaccine is not a live virus and the test is to detect live virus.

[canderson]

10 minutes ago, Jim_Iain said:

I also asked my doctor and he said there should be no problem as the vaccine is not a live virus and the test is to detect live virus.

Not really, though correct that the booster won't cause an issue.  The booster is neither live nor dead virus.

 

Re "live" virus detection...

 

The PCR tests looks for genetic material from the virus.  One reason PCR can continue to come up positive for some time after recovery is that PCR responds to leftover genetic material from a dead virus as well, hence the need for COR for those few who can't produce a negative result in a timely manner.

 

Antigen responds to proteins produced while the virus is active.

Edited September 28, 2022 by canderson

[cangelmd]

27 minutes ago, odysee said:

Thanks a lot - very reassuring as the gap between the planned booster and the required antigen test decreases continuously.  We might even still have to go last minute for a 2nd booster with the old vaccine 🫣

As someone else mentioned, it is still important to take precautions before cruising.

Im on a TA at the end of October, so I have to have a negative proctored test. It is thought maximum immunity develops about 2 weeks after a booster. I plan on masking, avoiding others as much as I can and periodic testing (I leave for Europe before I can test to board). I have 3 out of state trips planned before we fly to Rome, so I have a lot of opportunity to be exposed to people not in my everyday bubble!

 

Im a little surprised, you can’t get the bivalent vaccine, that’s the default for boosters here.

[canderson]

@cangelmd

We're on a TA, too, and just received the bivalent here.  We 4 will be in Barcelona for 4 days pre-cruise, and plan to test just as early as the two day limit allows.

[odysee]

1 hour ago, cangelmd said:

 

Im a little surprised, you can’t get the bivalent vaccine, that’s the default for boosters here.

Switzerland runs its own evaluation and validation process which takes additional time and hence was later in the ordering phase.