Fully Vaccinated
Fully Vaccinated
[Megan is standing in front of a three-step stair leading up to an open door. She has one hand in the air while talking to someone inside the house, who replies. The ground outside has small tufts of grass.] Megan: Hi, I'm here to visit! Voice, from inside the house: Do I know you? Megan: No, it's cool, I'm two weeks past my second dose.
[Caption below the panel:] Remember, once you're fully vaccinated, the CDC says you're free to visit other people's houses.

This comic is another in a series of comics related to the COVID-19 pandemic , specifically regarding the COVID-19 vaccine .
The Centers for Disease Control and Prevention (CDC) has stated that once people are fully vaccinated, they are able to visit other people's houses (and not risk spreading/catching coronavirus). The implication, of course, is that you can visit people that you would also have visited before the outbreak. The humor in this comic comes from Megan who is just going to visit a random stranger's house. She explains this is okay because she is fully vaccinated, telling the person in the house that she is two weeks past her second dose. This was part of the topic of the last vaccine comic 2450: Post Vaccine Social Scheduling .
Restrictions to socializing, brought in as various governments reacted to the emergent COVID-19 pandemic, often disallowed or discouraged visiting family, friends, etc, beyond a mutually isolating 'support bubble', which meant that many house visits that might have occurred beforehand were no longer advisable. With the development and distribution of vaccines, and the eventual receiving of a second dose as applicable, the rules have been modified to allow those vaccinated to once again resume some degree of their prior outgoing behavior where the risks have been mitigated.
In this instance, though, Megan has taken the advice even further. Rather than opening back up to a situation closer to the 'old normal', she has taken it as an official sanction to exceed the old social limits and pester complete strangers. Alternately, this is what she always used to do, and only stopped 'for the duration', this unlucky householder being (one of) the first to be subjected to this 'guerilla visiting' now that there seems to be no reason not to continue.
In the title text, the owner of the house explains to Megan that just because she has been vaccinated she just can't enter into someone's house without being invited — a commonly understood form of property law.
But due to the vaccine type Megan thinks the owner has mixed this up with a commonly understood element of vampire lore, that vampires must be invited into a home before they can pass through the doorway. 
In vampire lore, vampires are often able to transform into bats, and these two are thematically associated with each other. Since the coronavirus is likely a bat virome that has entered into humans, Megan misunderstands the owner's objection to her entry, believing that the homeowner thinks that she has become a vampire. (The virus, and thus elements of the vaccine, having ultimately originated in bats and therefore 'possibly' actual vampire stock.)
Megan thus begins to explain that the vaccine works on a bat virus and has nothing to do with bats. And since she is thus not a vampire she has no problems entering a doorway uninvited, and further explains that she is also not repelled by garlic or other classic weakness of vampires. Vampire lore states that they are repelled by garlic , crosses, holy water, sunlight, and wooden stakes through the heart (the last being a problem for humans in general, vampiric or otherwise).
The owner is attempting to explain that Megan does not have the legal or moral right to enter simply because she is vaccinated, but this seems to not register with Megan .
Doing ridiculous things that were never allowed, even normally, after being vaccinated or low-risk, was also the theme of 2434: Vaccine Guidance . 2391: Life Before the Pandemic also dealt with a similar theme, with Cueball and Megan reminiscing about activities they missed doing but which had not been allowed or possible before the pandemic.
[Megan is standing in front of a three-step stair leading up to an open door. She has one hand in the air while talking to someone inside the house, who replies. The ground outside has small tufts of grass.] Megan: Hi, I'm here to visit! Voice, from inside the house: Do I know you? Megan: No, it's cool, I'm two weeks past my second dose.
[Caption below the panel:] Remember, once you're fully vaccinated, the CDC says you're free to visit other people's houses.
