In the book "Headlines: Halachic Debates of Current Events" the author cites Rav Malkiel Tzvi Tannenbaum of Lomza in Divrei Malkiel 5:35
[...] We thus see that it is permissible to place oneself in a situation of possible danger, as long as there is only a remote risk. Elaboration is needed to explain the limits in this regard [...]
However, if you read the mentioned article, you'll find out that it is not that easy to define what is "a remote risk". Rav Eliezer Waldenberg (Tzitz Eliezer 9:17) applies this to doctors, who, due to their profession, need to help people and therefore can get in a hazardous situation (p. 276).
So, to this, Rav Elchanan Wasserman (Kovetz Shiurim, Ketubos 136) explains that when one is able to be careful and he is not (careful), he puts himself and his life at risk (p. 275).
Adapted from "Headlines: Halachic Debates of Current Events"
The Rambam (Mishneh Torah, Hilchos Rotzeach uShmirat Nefesh, chapter 11:4) explains that it is a positive mitzvah to remove any obstacle that might pose a danger to life:
Similarly, it is a positive mitzvah to remove any obstacle that could pose a danger to life, and to be very careful regarding these matters, as Deuteronomy 4:9 states: "Beware for yourself; and guard your soul." If a person leaves a dangerous obstacle and does not remove it, he negates the observance of a positive commandment, and violates the negative commandment: "Do not cause blood to be spilled."
So, if you are trying to get infected, for whatever the reason may be, according to Halacha, this is not allowed. The Torah tells us to "build a roof", e.g. guard your life and health, why would one breaks down the roof in order to "fall down the roof"?
The Sefer Chasidim (Siman 673) writes that if you have a skin-disease, you should not bathe with another person:
לפני עור לא תתן מכשול שלא ירחץ אדם שהוא מוכה שחין עם יהודי אחר אלא א"כ יודיענו שנאמר (ויקרא יט יח) ואהבת לרעך כמוך וכתיב (ויקרא יט טז) ולא תעמוד על דם רעך:
Answering your question
In your question, you ask:
Are there contemporary responsa specifically about the acceptability of "Corona parties"?
There is a great work called "Tzurba M’Rabanan, Special volume: Halachot of the COVID-19 Era" (2020) by Rav Benzion Algazi, see also the website. On page 330 they write:
Since it is known clearly that it harms others, it is obvious that not only is it an absolute prohibition [to be negligent about it] but the rules of damages also apply to it, like all cases of damaging another’s property.
On DinOnline the following story can be found from Rabbi Chaim Palagi:
Rabbi Chaim Palagi (Nishmas Kol Chai, volume 2, Choshen Mishpat chapter 69) was asked by a community regarding a physician who regularly treated infectious patients. The town’s residents were afraid to be infected by him. The community wanted to prevent the doctor from coming to shul to pray with them and asked Rabbi Chayim if it was permissible to do so. Rabbi Chaim instructed that if the doctor wished to pray he must construct barriers around his seat to separate him from his neighbors; he must enter the shul first and leave last (similar to the rules of a tzora’as patient, Negaim, chapter 13:12)
Lichtenstein, D. (2017). Headlines 2: Halachic Debates of Current Events. Menucha Publisher.
Algazi, B., & E. (2020). Tzurba M’Rabanan: Special Volume: Halachot of the COVID-19 Era. Mizrachi Press. https://web.colby.edu/coronaguidance/files/2021/11/Tzurba-Halachot-of-the-COVID-19-Era.pdf